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Surveillance mammography and stereotactic core breast biopsy for probably benign lesions: A cost comparison analysis
Surveillance Mammography and Stereotactic Core Breast Biopsy for Probably Benign Lesions: A Cost Comparison Analysis R. James Brenner, MD 1, Edward A. Sickles, MD 2
R a t i o n a l e a n d o b j e c t i v e s . The authors c o m p a r e d the economic effect of stereotactic core needle biopsy (CNB) with that of short-term unilateral surveillance m a m m o g r a p h y in the m a n a g e m e n t of probably benign breast lesions detected during routine screening m a m m o g r a p h y . M e t h o d s . Published data with regard to the cost of stereotactic CNB and unilateral m a m m o g r a p h y w e r e applied to 3,184 patients w h o t m d e r w e n t surveillance m a m m o g r a p h y , including 161 patients w h o u n d e r w e n t biopsy. Costs of immediate tissue diagnosis w e r e c o m p a r e d with costs of surveillance with use of ratios of published reimbursement scales to minimize geographic variations. Sensitivity analyses w e r e applied to this ratio. Results. The cost of managing probably benign breast lesions with surveillance m a m m o g r a p h y was $3,307,575 less than if all lesions had b e e n managed with CNB. The ratio of the cost of CNB to the cost of surveillance m a m m o g r a p h y was 8" 1. This ratio is m o r e sensitive to the frequency of use of CNB than to reimbursement schedules. C o n c l u s i o n . With similar false-negative rates, CNB is m o r e costly than surveillance and has a negative effect in the m a n a g e m e n t of probably benign breast lesions, unless interval change during surveillance p r o m p t s tissue diagnosis. K e y W o r d s . Breast neoplasms; breast radiography; economics, medical; radiology and radiologists, socioeconomic issues.
From the ~Eisenberg Keefer Breast Center, John Wayne Cancer Institute, St Johns Hospital and Health Center, Santa Monica, CA; and the aDepartrnent of Radiology, University of California School of Medicine, San Francisco, CA. Address reprint requests to R. J. Brenner, MD, Eisenberg Keefer Breast Center, John Wayne Cancer Institute, St Johns Hospital and Health Center, 1328 22nd St, Santa Monica, CA 90404. Received September 12, 1996, and accepted for publication after revision February 27, 1997. Acad Radiol 1997;4:419-425
©1997, Association of University Radiologists
though imaging-directed, fme-needle-aspiration tissue sampling (with skilled m a m m o g r a p h i c interpretation) has b e e n used successfully in Europe to avert surgical procedures, its use in the United States has b e e n limited. Among the reasons cited are the lack of widespread expertise in breast cytopathology, results that too often include cases of nondiagnostic material, and a medicolegal climate that favors m o r e definitive diagnosis. With the introduction of computer-assisted stereotactic and ultrasound (US)-directed large-core needle biopsies, w h i c h allow multiple samples to be obtained, the histologic material provided for diagnosis mitigates m a n y of these concerns. The relative accuracy of this p r o c e d u r e may depend on the specific type of lesion being sampled, but results from several clinical series provide a basis for favorable initial assessment of the accuracy of this
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procedure [1-11 ]. The lack of uniform criteria for reported results, together with insufficient follow-up data about lesions that have not b e e n subjected to excisional biopsy, prevents optimal assessment [6, 12]. The cost of core needle biopsy (CNB), however, has been reported uniformly to be less than that of surgery [1, 13, 14]. For example, Liberman et al [13] c o m p a r e d reimbursements on the basis of published data from Medicare and relative value for physician (RVP) scales to s h o w that the cost of excisional biopsy for nonpalpable breast lesions was twice that of CNB w h e n derivative costs of incomplete analysis by CNB are taken into accotmt. Most reported series of CNB failed to categorize the degree of (or lack of) suspicion of malignancy of m a m m o g r a p h i c lesions for w h i c h core biopsy was performed, with two exceptions: (a) In an early report, Dowlatshahi et al [2] examined 250 "relatively low-suspicion" lesions subject to tissue sampling and (b) Brenner et al [10] categorized lesions by using the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) in a validation study comparing the results of core biopsy to those of surgery. Of 145 malignancies in the latter study, 23% involved lesions assigned mammographically to category 2 (benign) or category 3 (probably benign, short-term follow-up r e c o m m e n d e d ) . Reasons for performing CNB for probably benign breast lesions include e x t r e m e anxiety, suspected noncompliance with surveillance m a m m o g r a p h y , and pregnancy or the expectation of p r e g n a n c y during the surveillance period. The use of surveillance m a m m o g raphy has b e e n s h o w n to increase the positive predictive value for any type of biopsy (eg, fine-needle aspiration, CNB, excision) to m o r e than 30% [14]. Thus, biopsy series that have a rate of malignancy of less than 30% are likely to include a substantial n u m b e r of benign and probably benign breast lesions that might otherwise have b e e n followed up successfully without intervention. In fact, the biopsy yield of malignancy in most CNB series reported by radiologists has b e e n less than 30% [1, 6-9]. This rate is even less than that reported by surgeons, ranging from 8% (34 of 416 lesions) to 18% (88 of 500 lesions) [15-17]. Mammographic surveillance of probably benign lesions detected and evaluated during screening mamm o g r a p h y has b e e n p r o p o s e d as a reasonable managem e n t strategy [18]. The feasibility of this a p p r o a c h
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has b e e n studied in t w o large series in w h i c h 0.5%2.0% of lesions eventually demonstrated malignancy, a percentage similar to that reported as "false-negative" in CNB series and as failed excisional biopsies [1-11, 19- 21 ]. Intuitively, the cost of m a m m o g r a p h i c surveillance for probably benign lesions should be less than that of biopsy, by means of either surgical excision or stereotactic core methods, although only theoretical models and c o m m e n t a r y have b e e n p r o p o s e d to substantiate this contention [22, 23]. In contrast, a favorable e c o n o m i c effect of CNB c o m p a r e d with excisional biopsy has b e e n directly evaluated from single institutions by using b o t h e c o n o m i c models and actual calculations from published data from Medicare and RVP scales [13, 24]. The p u r p o s e of this study was to evaluate the relative costs of managing probably benign, mammographically detected breast lesions. To this end, w e c o m p a r e d stereotactic CNB with surveillance m a m m o g r a p h y by using o u t c o m e data from a studied population and published costs that have b e e n applied to comparing the effect of CNB with that of surgery.
MATERIALS AND METHODS Perspective T h e p a r a m e t e r s f o r analyzing cost-effectiveness o f a
given p r o c e d u r e or intervention include multiple factors that have b e e n defined elsewhere [25], most of w h i c h are beyond the scope of this analysis and others of w h i c h must be addressed here. False-positive diagnoses from CNB are b o t h rare and unlikely to affect overall m a n a g e m e n t because subsequent wider surgical excision will help determine additional treatment. False-positive diagnoses f r o m surveillance mammograp h y - - t h a t is, a perceived change in the benign mammographic appearance of a lesion that p r o m p t s bio p s y - r e s u l t in an additional cost (of biopsy), w h i c h is accounted for in comparing overall costs of surveillance m a m m o g r a p h y versus CNB. False-negative rates from b o t h procedures have b e e n reported as equivalent [1-11, 19, 20], as have the likely economic and social effects of delay in diagnosis [25, 26]. Although to our knowledge other parameters involving health-related quality of life have not b e e n studied, they are presumably similar and the "effectiveness" of b o t h surveillance m a m m o g r a p h y and CNB are likely to be the same.
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A difference in cost should therefore offer a reasonable approximation of the "cost-effectiveness" relationship of both procedures. Induced costs as defined by Weinstein et al [27] are not germane to this discussion, so that the use of constant dollars provides a basis for direct comparison. This analysis will therefore focus on a comparison of direct costs of surveillance and CNB for probably benign breast lesions in a given population, based on published data. Because of the substantial frequency with w h i c h probably benign breast lesions are detected during screening mammography [18], the perspective will be societal, with a discussion that includes a sensitivity analysis regarding the effect on this analysis of variable procedural costs and diagnostic test performance.
Costs of Procedures Liberman et al [13] performed a cost comparison of CNB and excisional biopsy by using 1993 published Medicare and RVP data; they concluded that the cost of CNB, including a finite percentage of cases in which further excisional biopsy was required for def'mitive diagnosis, was half that of excisional biopsy. Hlllner et al [24] proposed a theoretical model to evaluate the economic effect of CNB on a breast biopsy program on the basis of specific cost-to-charges estimates for the authors' institution. In this model, the cost ratios of CNB to surgery with preoperative needle localization and biopsy were similar to those reported by Liberman et al. Although cost-to-charges estimates are used in other economic analyses to avoid the inconsistencies of Medicare payments and variabilities of facility charges, the comparable ratios of the data from the studies of Hillner et al and Liberman et al indicate that comparisons based on published rates may be useful as a basis for comparison of cost between the two procedures, even though the actual amounts vary [28, 29]. In comparing CNB to surgery, Liberman et al [13] reported adjusted costs (after considering additional surgery required for 23% of patients following CNB) as $733 for Medicare and $1,305 for RVP. Although 1993 data were no longer available at the time of this analysis, 1994 data that were comparable to the 1993 data were used to determine the cost of a unilateral mammographic examination as $64.96 ($65) for Medicare and $105.12 ($105) for RVP, the former being similar to the mammographic examination charge ($60) reported by Hillner et al [24].
Studied Population We used the data from 3,184 patients with screening-detected lesions diagnosed as probably benign; the patients were previously reported on by Sickles [19]. Excluded from this study were definitely benign lesions such as simple cysts or intramammary lymph nodes, as well as any lesion considered suspicious for malignancy. The cost of surveillance was determined as the cost of one additional short-term follow-up unilateral mammographic examination, as this population was one for w h i c h screening m a m m o g r a p h y would be performed routinely. Not reported previously but relevant to this cost analysis is the fact that 616 patients were at least 65 years old and 2,568 were younger than 65 years (E.A.S., unpublished data, 1996). Although some patients younger than 65 years may have received Medicare coverage through affiliated programs (eg, disability), a reasonable approximation in considering comparative costs may be made by assuming that the 616 older patients were covered by Medicare and the remaining 2,568 patients were covered by private insurance subject to RVP analysis. This population of patients would ordinarily be followed up for probably benign lesions, as categorized with ACR BI-RADS classification 3. Of the original 3,184 patients for w h o m surveillance was recommended, 12 initially requested and underwent biopsy to obtain tissue diagnosis. Another 18 patients underwent biopsy during the surveillance period because radiologists at other institutions were unwilling to accept a probably benign diagnosis or because the patients sought alternative surgical management elsewhere. Finally, during surveillance 131 lesions showed interval change prompting biopsy, for a total of 161 patients undergoing tissue diagnosis in this series. Of these, 41 patients were at least 65 years old and 120 were younger than 65 years (E.A.S. unpublished data, 1996). Because data were no longer available, the age distribution of the 12 patients w h o underwent biopsy before the end of the proposed surveillance period was extrapolated from the total population that underwent biopsy (there was a 3:1 ratio of non-Medicare to Medicare patients). Thus, nine patients under age 65 years and three aged 65 years or older would have been spared a single unilateral mammographic examination during the study period. For purposes of this analysis, the cost of managing Sickles' population with periodic surveillance mam-
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TABLE 1: Cost Comparison of Treating 3,184 Patients Recommended for Surveillance Mammography because of Probably Benign Lesions: Cost of Immediate Biopsy versus Surveillance Mammography with Selective Biopsy Surveillance Mammography and CNB Reimbursement Schedule
Medicare Additional unilateral mammogram* CNB RVP Additional unilateral mammogram* CNB Total
No. of Patients
Cost per Procedure ($)
Total Cost ($)
CNB at Initial Detection No. of Patients
Cost per Procedure ($)
Total Cost ($)
613 41
65 733
39,845 30,053
616
733
451,528
2,559 120 3,184
105 1,305 -.-
268,695 156,600 495,193
2,568
1,305
3,351,240
3,184
..-
3,802,768
Note.--From references 13 and 19. *Excludes 12 patients who chose immediate biopsy.
m o g r a p h y was determined by calculating the cost of a single additional unilateral m a m m o g r a p h i c examination for those patients w h o u n d e r w e n t this p r o c e d u r e (according to b o t h RVP and Medicare reimbursement schedules), plus the cost of CNB for those patients w h o u n d e r w e n t biopsy. This total cost was then c o m p a r e d with the cost of performing CNB in all 3,184 patients after the initial determination of a probably benign lesion, according to the same respective RVP and Medicare schedules. To evaluate further the cost relationship b e t w e e n surveillance m a m m o g r a p h y and immediate CNB in this population, w e analyzed the effects of varying reimb u r s e m e n t schedules and diagnostic p e r f o r m a n c e on this relationship. Specifically, the analysis was conducted for the actual population studied, for the same n u m b e r of patients b y using only Medicare scales, and for the same n u m b e r of patients by using only RVP scales. The effect of decreased diagnostic p e r f o r m a n c e and consequent increased use of CNB during the surveillance period was also evaluated.
RESULTS
With use of the published n u m b e r s discussed previously for purposes of comparison, the cost of managing the population studied by Sickles [19] is initially app r o x i m a t e d as the cost of an additional m a m m o g r a p h i c examination for 616 patients covered by Medicare ($65 p e r case), or $40,040, plus the cost for 2,568 patients covered by private insurance at RVP values ($105 p e r case), or $269,640, for a total of $309,680. To this number is added the cost for 161 patients w h o u n d e r w e n t
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biopsy (assuming CNB rather than surgical biopsy). Thus, 41 patients covered by Medicare ($733 p e r case) would cost $30,053 and 120 patients covered by RVP would cost $156,600, for a total of $186,653. From these calculations, the cost of the single unilateral surveillance m a m m o g r a p h i c examination for the 12 patients w h o sought initial tissue diagnosis is subtracted. Thus, the cost of a single m a m m o g r a p h i c examination for nine patients at RVP values ($105 p e r study = $945) and three patients at Medicare values ($65 p e r study = $195), or $1,140, would not have b e e n incurred. Therefore, the total cost of managing this studied population would be $309,680 plus $186,653 less $1,140, w h i c h is $495,193 (Table 1). The cost of evaluating all of these patients initially with CNB is calculated for comparative purposes by using the same scales, as adjusted by Liberman et al [13] to account for the 23% of CNB patients w h o required additional surgery owing to indeterminate or incomplete tissue sampling with CNB. Thus, 616 patients covered by Medicare ($733 p e r case) w o u l d cost $451,528 and 2,568 patients covered by RVP ($1,305 p e r case) would cost $3,351,240, for a total of $3,802,768 (Table 1). The difference in managing Sickles' population of 3,184 patients with probably benign lesions with surveillance m a m m o g r a p h y and selected intervention to diagnose existing cancer is therefore $3,802,768 less $495, 193, or $3,307,575. During the 8-year study period, this would m e a n a realized savings of $413,446 p e r year or a savings of $1,039 p e r patient. Adjusting for variabilities in absolute amounts, the ratio of cost for CNB c o m p a r e d to cost for surveillance is thus about 8:1 for this population.
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The validity of this ratio is substantiated b y applying either the RVP or Medicare reimbursement schedules to all patients in this population. For example, if only the RVP scales w e r e chosen for b o t h CNB in all 161 patients and the additional unilateral m a m m o g r a p h i c examination in the 3,023 patients (less the 12 patients requesting immediate biopsy), the cost of managing the population w o u l d be $526,260. The cost for CNB in all patients w o u l d be $3,555,120 and, thus, the CNB-tosurveillance ratio w o u l d be 6.8:1 (3,184 CNB at $1,305 = $ 3,555,120; additional m a m m o g r a p h i c study in 3,011 patients at $105 = $316,155 + 161 CNBs at $1,305 = $210,105, for a total of $526,260). A similar calculation performed by using only Medicare scales yields a ratio of 7.4:1 (3,184 CNBs at $733 = $2,333,872; additional m a m m o g r a p h i c study in 3,011 patients at $65 = $195,715 + 161 CNBs at $733 = $118,013, for a total of $313,728). It is m o r e difficult to assess the effect of diagnostic test p e r f o r m a n c e because rates of r e c o m m e n d a t i o n for biopsy are even less standardized than reimbursement schedules. Assuming that twice as m a n y biopsies would be requested during the surveillance period (assigned to b o t h the Medicare- and RVP-covered populations), the effect on this ratio is relatively small, but not trivial. With use of the same Medicare and RVP schedules described by Liberman et al [13] and by doubling the n u m b e r of respective patients undergoing biopsy sometime during the surveillance period, biopsy costs in the population w o u l d be calculated as follows: 82 patients (Medicare) at $733 p e r CNB + 575 patients (Medicare) at $65 p e r additional m a m m o g r a p h y + 240 patients (RVP) at $1,305 p e r CNB + 27448 patients (RVP) at $105 p e r additional m a m m o g r a p h y , or $97,481 (Medicare) + $570,240 (RVP) = $667,721. The cost of treating all patients with CNB does not change, and thus the cost-savings ratio of r e c o m m e n d i n g twice as m a n y biopsies as actually p e r f o r m e d in this studied population bec o m e s $3,802,768/$6,667,721, or 5.6:1.
DISCUSSION The cost of managing probably benign lesions with surgical biopsy has b e e n a source of criticism of screening m a m m o g r a p h y programs [30]. As an alternative, CNB has b e e n s h o w n to be an effective m e t h o d of achieving tissue diagnosis [1-9]; it is comparable in accuracy to surgery but less expensive [13]. Lindfors and Rosenqulst [22] p r o p o s e d a theoretical
model for evaluating the economic effect of incorporating core breast biopsy into a m a m m o g r a p h y practice. W h e n the marginal cost of years of life saved in screening was evaluated, the effect of CNB was d e p e n d e n t primarily on the frequency with w h i c h it was used. Substitution of CNB for surgical biopsy in lesions requiring tissue diagnosis (ACR BI-RADS categories 4 and 5) resulted in substantial cost savings. This favorable e c o n o m i c effect was reversed, however, if core biopsies also w e r e p e r f o r m e d instead of surveillance mamm o g r a p h y for probably benign breast lesions (ACR BIRADS category 3). Assuming that CNB was used in 90% of category 3 cases, w h i c h could have b e e n managed appropriately by means of periodic m a m m o g r a p h i c follow-up, their model predicted an overall cost increase to a screening p r o g r a m of 31%. Our analysis of a studied population subjected to surveillance m a m m o g r a p h y , including m a n y w o m e n w h o u n d e r w e n t biopsy, reflects the actual circumstances of clinical practice. This population, therefore, provides a meaningful basis for comparing costs of follow-up mamm o g r a p h y with those of CNB, especially because the false-negative o u t c o m e rates of surveillance mammograp h y and CNB are comparable [1, 19, 21]. With use of published n u m b e r s from Medicare and RVP scales, the ratio of savings with surveillance m a m m o g r a p h y instead of CNB for probably benign lesions is approximately 8:1. This analysis should not be affected substantially by the k n o w n variability of Medicare and RVP scales in different areas of the country because the same Medicare and RVP scales are used as a basis for comparison of b o t h surveillance m a m m o g r a p h y and CNB and because the ratios of Medicare and RVP costs (not absolute dollar amounts) for rate of reimbursement of surveillance versus CNB are similar. Note that the cost of CNB will be slightly higher for those institutions that choose to p e r f o r m a single, unilateral, 6-month follow-up m a m m o g r a p h i c examination following benign core biopsy [31]. Our analysis provides a basis for understanding the difference in m a n a g e m e n t costs b e t w e e n surveillance m a m m o g r a p h y and CNB for probably benign lesions. Although CNB has b e e n s h o w n to be less expensive than surgical biopsy for lesions requiring tissue diagnosis, it is considerably m o r e expensive than surveillance m a m m o g r a p h y for probably benign lesions. The costsavings ratio is sensitive to reimbursement scales, showing a greater savings with the lower reimbursem e n t scales used for Medicare (7.4:1) than for RVP
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(6.8:1): The cost-savings ratio is even more sensitive in a negative manner to the use of CNB, showing a decrease to 5.6:1 if twice as many lesions in this studied population were subject to CNB, with no demonstrable change in o u t c o m e because the additional lesions sampled for biopsy would be benign. The low yield of malignancy (especially w h e n less than 20%) from many CNB series suggests that the ready availability of this technology may p r o m p t management by means of tissue diagnosis, although surveillance may be an equally accurate and m u c h less costly approach [1-4, 15-17]. Large prospective mammographic studies indicate a yield of malignancy of 38%47% w h e n tissue diagnosis is obtained only for those lesions that are truly suspicious for malignancy (ie, ACR BI-RADS categories 4 and 5) [14]. Because clinical outcomes for both approaches appear to be similar, cost factors b e c o m e increasingly important w h e n management strategies are being devised, especially in an era of managed care and strict utilization review [6, 10, 19211. The effect of delayed diagnosis of a mammographically detected lesion that is eventually s h o w n to be malignant is difficult to determine in any given case. However, becanse false-negative rates from published studies of surveillance, CNB, and surgical biopsy are similar, the effect is likely to be similar for all three approaches. Data from a national malpractice study concerning delayed diagnosis of breast cancer indicate substantial plaintiff awards for delays of 6 months to 1 year, but these data involved a majority of patients with clinical signs or symptoms of cancer [32]. These circumstances are different from those involving asymptomatic patients with mammographically detected lesions that are probably benign. Reported data suggest that probably benign lesions that have been followed up and eventually s h o w n to be cancer have a (favorable) prognosis similar to that of screening-detected cancers [14]. Indeed, unpublished follow-up data from the studied population reported herein demonstrate that all patients w h o were placed into surveillance but were later found to have cancer are alive and disease-free 120 months after the initial detection (E.A.S., unpublished data, 1997). At least one appellate court has dismissed claims for damages of a benign-appearing mammographic mass that grew from 3 to 9 m m in diameter before a malignant diagnosis was established; the patient showed no evidence of axillary node involvement or other spread of disease [33].
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We have not examined the comparative costs of USguided CNB and surveillance m a m m o g r a p h y because, to our knowledge, there are no published data about the subject. In addition, different protocols involving CNB may include short-term follow-up mammography; this would add to the cost of the procedure but has not been considered here because of the inconsistency with w h i c h this approach is used [9]. Although the cost of CNB has a positive economic effect (reduced cost) on the diagnosis of malignancy compared with excisional biopsy, w e have shown that the procedure has a substantially negative economic effect in the treatment of patients with probably benign breast lesions detected with screening mammography. This negative effect is accentuated by the lower reimbursement scales used by Medicare compared with RVP values, and it is even more dependent on the frequency with w h i c h CNB is used in a population of patients with lesions that have a very low likelihood of malignancy. REFERENCES 1. Parker SH, Lovin JD, Jobe WE, et al. Nonpalpable breast lesions: stereotactic automated large-core biopsies. Radiology 1991 ;180:403-407. 2. Dowlatshahi K, Yaremko ML, Kluskens LF, et al. Nonpalpable breast lesions: findings of stereotaxic needle core biopsy and fine-needle aspiration cytology. Radiology 1991 ;181:745-750. 3. Dronkers DJ. Stereotaxic core biopsy of breast lesions. Radiology 1992; 183:631-634. 4. Elvecrog EL, Lechner MC, Nelson MT. Nonpalpable breast lesions: correlation of stereotaxic large-core needle biopsy and surgical biopsy results. Radiology 1993; 188:453-455. 5. Sullivan DC. Needle core biopsy of mammographic lesions. A JR 1994; 162:601-608. 6. Parker SH, Burbank F, Jackman RJ, et al. Percutaneous large-core breast biopsy: a multi-institutional study. Radiology1994;193:359-364. 7. Caines JS, McPhee MD, Konok GP, et ai. Stereotaxic needle core biopsy of breast lesions using a regular mammographic table with an adaptable stereotaxic device. AJR 1994; 163:317-321. 8. Jackman RJ, Newels KW, Shepard MJ, et ai. Stereotaxic large-core needle biopsy of 450 nonpalpable breast lesions with surgical correlation in lesions with cancer or atypical hyperplasia. Radiology1994; 193:91-95. 9. Doyle A J, Murray KA, Nelson EW, et al. Selective use of image-guided large-core needle biopsy of the breast: accuracy and cost-effectiveness. AJR 1995; 165:281-284. 10. Brenner RJ, Fajardo L, Fisher PR, et ai. Percutaneous core biopsy of the breast: effect of operator experience and number of samples on diagnostic accuracy. AJR 1996; 166:341-346. 11. Caines JS, Chantziantoniou K, Wright BA, et al. Nova Scotia breast screening program experience: use of needle core biopsy in the diagnosis of screening-detected abnormalities. Radiology 1996; 198:125130. 12. Brenner RJ. Interventional procedures of the breast: medicolegal considerations. Radiology 1995; 195:611-615. 13. Liberman L, Fahs MC, Dershaw DD, et al. Impact of stereotaxic core breast biopsy on cost of diagnosis. Radiology1995;195:633-637. 14. Sickles EA. Management of probably benign breast lesions. Radiol Clin North Am 1996;33:1123-1130. 15. Janes RH, Bouton MS. Initial 300 consecutive stereotactic core-needle breast biopsies by a surgical group. Am J Surg 1994; 168:533-537.
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16. Mikhail RA, Nathan RC, Weiss M, et al. Stereotactic core needle biopsy of mammographic breast lesions as a viable alternative to surgical biopsy. Ann Surg Oncol 1994;1:363-367. 17. Israel PZ, Fine RE. Stereotactic needle biopsy for occult breast lesions: a minimally invasive alternative. Am Surg 1996;61:87-91. 18. Brenner RJ, Sickles EA. Acceptability of periodic follow-up as an alternative to biopsy for mammographically detected lesions interpreted as probably benign. Radiology1989;171:645-646. 19. Sickles EA. Periodic mammographic follow-up of probably benign lesions: results in 3,184 consecutive cases. Radiology 1991 ;179:463468. 20. Varas X, Leborgne F, Leborgne JH. Nonpalpable, probably benign lesions: role of follow-up mammography. Radiology 1992; 184:409-414. 21. Homer MJ. Pre-biopsy needle localization: methods, problems and expected results. Radiol Clin North Am 1992;30:139-153. 22. Lindfors KK, Rosenquist CJ. Needle core biopsy guided with mammography: a study of cost-effectiveness. Radiology 1994;190:217-222. 23. Sickles EA, Parker SH. Appropriate role of core breast biopsy in the management of probably benign lesions. Radiology 1993; 188:315. 24. Hillner BE, Bear HD, Fajardo LL. Estimating the cost-effectiveness of stereotaxic biopsy for nonpalpable breast abnormalities: a decision analysis model. Acad Radio11996;3:351-360. 25. Russell LB, Gold MR, Spiegel JE, et al. The role of cost-effectiveness analysis in health and medicine. JAMA 1996;276:1172-1177.
26. Sickles EA. Nonpalpable, circumscribed, noncalcified solid breast masses: likelihood of malignancy based on lesion size and age of patient. Radiology 1994; 192:39-44. 27. Weinstein MC, Siegel JE, Gold MR, et al. Recommendations of the panel on cost-effectiveness in health and medicine. JAMA 1996;276: 1253-1258. 28. Hillner BE, Smith T J, Desch CE. Efficacy and cost-effectiveness of autologous bone marrow transplantation in metastatic breast cancer: estimates using decision analysis while awaiting clinical trial results. JAMA 1992;267:2055-2061. 29. Hillner BE, Smith TJ. Efficacy and cost effectiveness of adjuvant chemotherapy in women with node-negative breast cancer: a decisionanalysis model. N Engl J Med 1991 ;324:160-168. 30. Eddy DM. Screening for breast cancer. Ann Intern Med 1989; 111:389399. 31. Doyle AJ, Murray KA, Nelson EW, et al. Selective use of image-guided large-core needle biopsy of the breast: accuracy and cost-effectiveness. AJR 1995; 165:281-284. 32. Physicians Insurers Association of America. The breast cancer study. Washington, DC: Physicians Insurers Association of America, 1995. 33. Bossio v Fiorillo, 210 AD 836, 620 NYS 596 (NY App 1994).
Announcement The Office of Continuing Medical Education of the University of Michigan Medical School is sponsoring a conference entitled " 1 9 t h A n n u a l S e m i n a r i n D i a g n o s t i c U l t r a s o u n d " September 11-12, 1997, at the Towsley Center, University of Michigan Medical Center, Ann Arbor, MI. The course will review currently used techniques and applications of diagnostic ultrasound and emphasize n e w information and advances in this field, especially fetal imaging, obstetrics applications, D o p p l e r technique, and color flow imaging. Fifteen credit hours in category 1 of the Physician's Recognition Award of the American Medical Association will be available. (Other credits by specialty may apply.) The course director is Terry M. Silver, MD. For m o r e information, contact the registrar, Towsley Center for Continuing Medical Education, Department of Postgraduate Medicine and Health Care Professions, University of Michigan Medical School, PO Box 1157, Ann Arbor, MI 48106-1157; (313) 763-1400.
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R a t i o n a l e a n d o b j e c t i v e s . The authors c o m p a r e d the economic effect of stereotactic core needle biopsy (CNB) with that of short-term unilateral surveillance m a m m o g r a p h y in the m a n a g e m e n t of probably benign breast lesions detected during routine screening m a m m o g r a p h y . M e t h o d s . Published data with regard to the cost of stereotactic CNB and unilateral m a m m o g r a p h y w e r e applied to 3,184 patients w h o t m d e r w e n t surveillance m a m m o g r a p h y , including 161 patients w h o u n d e r w e n t biopsy. Costs of immediate tissue diagnosis w e r e c o m p a r e d with costs of surveillance with use of ratios of published reimbursement scales to minimize geographic variations. Sensitivity analyses w e r e applied to this ratio. Results. The cost of managing probably benign breast lesions with surveillance m a m m o g r a p h y was $3,307,575 less than if all lesions had b e e n managed with CNB. The ratio of the cost of CNB to the cost of surveillance m a m m o g r a p h y was 8" 1. This ratio is m o r e sensitive to the frequency of use of CNB than to reimbursement schedules. C o n c l u s i o n . With similar false-negative rates, CNB is m o r e costly than surveillance and has a negative effect in the m a n a g e m e n t of probably benign breast lesions, unless interval change during surveillance p r o m p t s tissue diagnosis. K e y W o r d s . Breast neoplasms; breast radiography; economics, medical; radiology and radiologists, socioeconomic issues.
From the ~Eisenberg Keefer Breast Center, John Wayne Cancer Institute, St Johns Hospital and Health Center, Santa Monica, CA; and the aDepartrnent of Radiology, University of California School of Medicine, San Francisco, CA. Address reprint requests to R. J. Brenner, MD, Eisenberg Keefer Breast Center, John Wayne Cancer Institute, St Johns Hospital and Health Center, 1328 22nd St, Santa Monica, CA 90404. Received September 12, 1996, and accepted for publication after revision February 27, 1997. Acad Radiol 1997;4:419-425
©1997, Association of University Radiologists
though imaging-directed, fme-needle-aspiration tissue sampling (with skilled m a m m o g r a p h i c interpretation) has b e e n used successfully in Europe to avert surgical procedures, its use in the United States has b e e n limited. Among the reasons cited are the lack of widespread expertise in breast cytopathology, results that too often include cases of nondiagnostic material, and a medicolegal climate that favors m o r e definitive diagnosis. With the introduction of computer-assisted stereotactic and ultrasound (US)-directed large-core needle biopsies, w h i c h allow multiple samples to be obtained, the histologic material provided for diagnosis mitigates m a n y of these concerns. The relative accuracy of this p r o c e d u r e may depend on the specific type of lesion being sampled, but results from several clinical series provide a basis for favorable initial assessment of the accuracy of this
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procedure [1-11 ]. The lack of uniform criteria for reported results, together with insufficient follow-up data about lesions that have not b e e n subjected to excisional biopsy, prevents optimal assessment [6, 12]. The cost of core needle biopsy (CNB), however, has been reported uniformly to be less than that of surgery [1, 13, 14]. For example, Liberman et al [13] c o m p a r e d reimbursements on the basis of published data from Medicare and relative value for physician (RVP) scales to s h o w that the cost of excisional biopsy for nonpalpable breast lesions was twice that of CNB w h e n derivative costs of incomplete analysis by CNB are taken into accotmt. Most reported series of CNB failed to categorize the degree of (or lack of) suspicion of malignancy of m a m m o g r a p h i c lesions for w h i c h core biopsy was performed, with two exceptions: (a) In an early report, Dowlatshahi et al [2] examined 250 "relatively low-suspicion" lesions subject to tissue sampling and (b) Brenner et al [10] categorized lesions by using the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) in a validation study comparing the results of core biopsy to those of surgery. Of 145 malignancies in the latter study, 23% involved lesions assigned mammographically to category 2 (benign) or category 3 (probably benign, short-term follow-up r e c o m m e n d e d ) . Reasons for performing CNB for probably benign breast lesions include e x t r e m e anxiety, suspected noncompliance with surveillance m a m m o g r a p h y , and pregnancy or the expectation of p r e g n a n c y during the surveillance period. The use of surveillance m a m m o g raphy has b e e n s h o w n to increase the positive predictive value for any type of biopsy (eg, fine-needle aspiration, CNB, excision) to m o r e than 30% [14]. Thus, biopsy series that have a rate of malignancy of less than 30% are likely to include a substantial n u m b e r of benign and probably benign breast lesions that might otherwise have b e e n followed up successfully without intervention. In fact, the biopsy yield of malignancy in most CNB series reported by radiologists has b e e n less than 30% [1, 6-9]. This rate is even less than that reported by surgeons, ranging from 8% (34 of 416 lesions) to 18% (88 of 500 lesions) [15-17]. Mammographic surveillance of probably benign lesions detected and evaluated during screening mamm o g r a p h y has b e e n p r o p o s e d as a reasonable managem e n t strategy [18]. The feasibility of this a p p r o a c h
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has b e e n studied in t w o large series in w h i c h 0.5%2.0% of lesions eventually demonstrated malignancy, a percentage similar to that reported as "false-negative" in CNB series and as failed excisional biopsies [1-11, 19- 21 ]. Intuitively, the cost of m a m m o g r a p h i c surveillance for probably benign lesions should be less than that of biopsy, by means of either surgical excision or stereotactic core methods, although only theoretical models and c o m m e n t a r y have b e e n p r o p o s e d to substantiate this contention [22, 23]. In contrast, a favorable e c o n o m i c effect of CNB c o m p a r e d with excisional biopsy has b e e n directly evaluated from single institutions by using b o t h e c o n o m i c models and actual calculations from published data from Medicare and RVP scales [13, 24]. The p u r p o s e of this study was to evaluate the relative costs of managing probably benign, mammographically detected breast lesions. To this end, w e c o m p a r e d stereotactic CNB with surveillance m a m m o g r a p h y by using o u t c o m e data from a studied population and published costs that have b e e n applied to comparing the effect of CNB with that of surgery.
MATERIALS AND METHODS Perspective T h e p a r a m e t e r s f o r analyzing cost-effectiveness o f a
given p r o c e d u r e or intervention include multiple factors that have b e e n defined elsewhere [25], most of w h i c h are beyond the scope of this analysis and others of w h i c h must be addressed here. False-positive diagnoses from CNB are b o t h rare and unlikely to affect overall m a n a g e m e n t because subsequent wider surgical excision will help determine additional treatment. False-positive diagnoses f r o m surveillance mammograp h y - - t h a t is, a perceived change in the benign mammographic appearance of a lesion that p r o m p t s bio p s y - r e s u l t in an additional cost (of biopsy), w h i c h is accounted for in comparing overall costs of surveillance m a m m o g r a p h y versus CNB. False-negative rates from b o t h procedures have b e e n reported as equivalent [1-11, 19, 20], as have the likely economic and social effects of delay in diagnosis [25, 26]. Although to our knowledge other parameters involving health-related quality of life have not b e e n studied, they are presumably similar and the "effectiveness" of b o t h surveillance m a m m o g r a p h y and CNB are likely to be the same.
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A difference in cost should therefore offer a reasonable approximation of the "cost-effectiveness" relationship of both procedures. Induced costs as defined by Weinstein et al [27] are not germane to this discussion, so that the use of constant dollars provides a basis for direct comparison. This analysis will therefore focus on a comparison of direct costs of surveillance and CNB for probably benign breast lesions in a given population, based on published data. Because of the substantial frequency with w h i c h probably benign breast lesions are detected during screening mammography [18], the perspective will be societal, with a discussion that includes a sensitivity analysis regarding the effect on this analysis of variable procedural costs and diagnostic test performance.
Costs of Procedures Liberman et al [13] performed a cost comparison of CNB and excisional biopsy by using 1993 published Medicare and RVP data; they concluded that the cost of CNB, including a finite percentage of cases in which further excisional biopsy was required for def'mitive diagnosis, was half that of excisional biopsy. Hlllner et al [24] proposed a theoretical model to evaluate the economic effect of CNB on a breast biopsy program on the basis of specific cost-to-charges estimates for the authors' institution. In this model, the cost ratios of CNB to surgery with preoperative needle localization and biopsy were similar to those reported by Liberman et al. Although cost-to-charges estimates are used in other economic analyses to avoid the inconsistencies of Medicare payments and variabilities of facility charges, the comparable ratios of the data from the studies of Hillner et al and Liberman et al indicate that comparisons based on published rates may be useful as a basis for comparison of cost between the two procedures, even though the actual amounts vary [28, 29]. In comparing CNB to surgery, Liberman et al [13] reported adjusted costs (after considering additional surgery required for 23% of patients following CNB) as $733 for Medicare and $1,305 for RVP. Although 1993 data were no longer available at the time of this analysis, 1994 data that were comparable to the 1993 data were used to determine the cost of a unilateral mammographic examination as $64.96 ($65) for Medicare and $105.12 ($105) for RVP, the former being similar to the mammographic examination charge ($60) reported by Hillner et al [24].
Studied Population We used the data from 3,184 patients with screening-detected lesions diagnosed as probably benign; the patients were previously reported on by Sickles [19]. Excluded from this study were definitely benign lesions such as simple cysts or intramammary lymph nodes, as well as any lesion considered suspicious for malignancy. The cost of surveillance was determined as the cost of one additional short-term follow-up unilateral mammographic examination, as this population was one for w h i c h screening m a m m o g r a p h y would be performed routinely. Not reported previously but relevant to this cost analysis is the fact that 616 patients were at least 65 years old and 2,568 were younger than 65 years (E.A.S., unpublished data, 1996). Although some patients younger than 65 years may have received Medicare coverage through affiliated programs (eg, disability), a reasonable approximation in considering comparative costs may be made by assuming that the 616 older patients were covered by Medicare and the remaining 2,568 patients were covered by private insurance subject to RVP analysis. This population of patients would ordinarily be followed up for probably benign lesions, as categorized with ACR BI-RADS classification 3. Of the original 3,184 patients for w h o m surveillance was recommended, 12 initially requested and underwent biopsy to obtain tissue diagnosis. Another 18 patients underwent biopsy during the surveillance period because radiologists at other institutions were unwilling to accept a probably benign diagnosis or because the patients sought alternative surgical management elsewhere. Finally, during surveillance 131 lesions showed interval change prompting biopsy, for a total of 161 patients undergoing tissue diagnosis in this series. Of these, 41 patients were at least 65 years old and 120 were younger than 65 years (E.A.S. unpublished data, 1996). Because data were no longer available, the age distribution of the 12 patients w h o underwent biopsy before the end of the proposed surveillance period was extrapolated from the total population that underwent biopsy (there was a 3:1 ratio of non-Medicare to Medicare patients). Thus, nine patients under age 65 years and three aged 65 years or older would have been spared a single unilateral mammographic examination during the study period. For purposes of this analysis, the cost of managing Sickles' population with periodic surveillance mam-
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TABLE 1: Cost Comparison of Treating 3,184 Patients Recommended for Surveillance Mammography because of Probably Benign Lesions: Cost of Immediate Biopsy versus Surveillance Mammography with Selective Biopsy Surveillance Mammography and CNB Reimbursement Schedule
Medicare Additional unilateral mammogram* CNB RVP Additional unilateral mammogram* CNB Total
No. of Patients
Cost per Procedure ($)
Total Cost ($)
CNB at Initial Detection No. of Patients
Cost per Procedure ($)
Total Cost ($)
613 41
65 733
39,845 30,053
616
733
451,528
2,559 120 3,184
105 1,305 -.-
268,695 156,600 495,193
2,568
1,305
3,351,240
3,184
..-
3,802,768
Note.--From references 13 and 19. *Excludes 12 patients who chose immediate biopsy.
m o g r a p h y was determined by calculating the cost of a single additional unilateral m a m m o g r a p h i c examination for those patients w h o u n d e r w e n t this p r o c e d u r e (according to b o t h RVP and Medicare reimbursement schedules), plus the cost of CNB for those patients w h o u n d e r w e n t biopsy. This total cost was then c o m p a r e d with the cost of performing CNB in all 3,184 patients after the initial determination of a probably benign lesion, according to the same respective RVP and Medicare schedules. To evaluate further the cost relationship b e t w e e n surveillance m a m m o g r a p h y and immediate CNB in this population, w e analyzed the effects of varying reimb u r s e m e n t schedules and diagnostic p e r f o r m a n c e on this relationship. Specifically, the analysis was conducted for the actual population studied, for the same n u m b e r of patients b y using only Medicare scales, and for the same n u m b e r of patients by using only RVP scales. The effect of decreased diagnostic p e r f o r m a n c e and consequent increased use of CNB during the surveillance period was also evaluated.
RESULTS
With use of the published n u m b e r s discussed previously for purposes of comparison, the cost of managing the population studied by Sickles [19] is initially app r o x i m a t e d as the cost of an additional m a m m o g r a p h i c examination for 616 patients covered by Medicare ($65 p e r case), or $40,040, plus the cost for 2,568 patients covered by private insurance at RVP values ($105 p e r case), or $269,640, for a total of $309,680. To this number is added the cost for 161 patients w h o u n d e r w e n t
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biopsy (assuming CNB rather than surgical biopsy). Thus, 41 patients covered by Medicare ($733 p e r case) would cost $30,053 and 120 patients covered by RVP would cost $156,600, for a total of $186,653. From these calculations, the cost of the single unilateral surveillance m a m m o g r a p h i c examination for the 12 patients w h o sought initial tissue diagnosis is subtracted. Thus, the cost of a single m a m m o g r a p h i c examination for nine patients at RVP values ($105 p e r study = $945) and three patients at Medicare values ($65 p e r study = $195), or $1,140, would not have b e e n incurred. Therefore, the total cost of managing this studied population would be $309,680 plus $186,653 less $1,140, w h i c h is $495,193 (Table 1). The cost of evaluating all of these patients initially with CNB is calculated for comparative purposes by using the same scales, as adjusted by Liberman et al [13] to account for the 23% of CNB patients w h o required additional surgery owing to indeterminate or incomplete tissue sampling with CNB. Thus, 616 patients covered by Medicare ($733 p e r case) w o u l d cost $451,528 and 2,568 patients covered by RVP ($1,305 p e r case) would cost $3,351,240, for a total of $3,802,768 (Table 1). The difference in managing Sickles' population of 3,184 patients with probably benign lesions with surveillance m a m m o g r a p h y and selected intervention to diagnose existing cancer is therefore $3,802,768 less $495, 193, or $3,307,575. During the 8-year study period, this would m e a n a realized savings of $413,446 p e r year or a savings of $1,039 p e r patient. Adjusting for variabilities in absolute amounts, the ratio of cost for CNB c o m p a r e d to cost for surveillance is thus about 8:1 for this population.
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The validity of this ratio is substantiated b y applying either the RVP or Medicare reimbursement schedules to all patients in this population. For example, if only the RVP scales w e r e chosen for b o t h CNB in all 161 patients and the additional unilateral m a m m o g r a p h i c examination in the 3,023 patients (less the 12 patients requesting immediate biopsy), the cost of managing the population w o u l d be $526,260. The cost for CNB in all patients w o u l d be $3,555,120 and, thus, the CNB-tosurveillance ratio w o u l d be 6.8:1 (3,184 CNB at $1,305 = $ 3,555,120; additional m a m m o g r a p h i c study in 3,011 patients at $105 = $316,155 + 161 CNBs at $1,305 = $210,105, for a total of $526,260). A similar calculation performed by using only Medicare scales yields a ratio of 7.4:1 (3,184 CNBs at $733 = $2,333,872; additional m a m m o g r a p h i c study in 3,011 patients at $65 = $195,715 + 161 CNBs at $733 = $118,013, for a total of $313,728). It is m o r e difficult to assess the effect of diagnostic test p e r f o r m a n c e because rates of r e c o m m e n d a t i o n for biopsy are even less standardized than reimbursement schedules. Assuming that twice as m a n y biopsies would be requested during the surveillance period (assigned to b o t h the Medicare- and RVP-covered populations), the effect on this ratio is relatively small, but not trivial. With use of the same Medicare and RVP schedules described by Liberman et al [13] and by doubling the n u m b e r of respective patients undergoing biopsy sometime during the surveillance period, biopsy costs in the population w o u l d be calculated as follows: 82 patients (Medicare) at $733 p e r CNB + 575 patients (Medicare) at $65 p e r additional m a m m o g r a p h y + 240 patients (RVP) at $1,305 p e r CNB + 27448 patients (RVP) at $105 p e r additional m a m m o g r a p h y , or $97,481 (Medicare) + $570,240 (RVP) = $667,721. The cost of treating all patients with CNB does not change, and thus the cost-savings ratio of r e c o m m e n d i n g twice as m a n y biopsies as actually p e r f o r m e d in this studied population bec o m e s $3,802,768/$6,667,721, or 5.6:1.
DISCUSSION The cost of managing probably benign lesions with surgical biopsy has b e e n a source of criticism of screening m a m m o g r a p h y programs [30]. As an alternative, CNB has b e e n s h o w n to be an effective m e t h o d of achieving tissue diagnosis [1-9]; it is comparable in accuracy to surgery but less expensive [13]. Lindfors and Rosenqulst [22] p r o p o s e d a theoretical
model for evaluating the economic effect of incorporating core breast biopsy into a m a m m o g r a p h y practice. W h e n the marginal cost of years of life saved in screening was evaluated, the effect of CNB was d e p e n d e n t primarily on the frequency with w h i c h it was used. Substitution of CNB for surgical biopsy in lesions requiring tissue diagnosis (ACR BI-RADS categories 4 and 5) resulted in substantial cost savings. This favorable e c o n o m i c effect was reversed, however, if core biopsies also w e r e p e r f o r m e d instead of surveillance mamm o g r a p h y for probably benign breast lesions (ACR BIRADS category 3). Assuming that CNB was used in 90% of category 3 cases, w h i c h could have b e e n managed appropriately by means of periodic m a m m o g r a p h i c follow-up, their model predicted an overall cost increase to a screening p r o g r a m of 31%. Our analysis of a studied population subjected to surveillance m a m m o g r a p h y , including m a n y w o m e n w h o u n d e r w e n t biopsy, reflects the actual circumstances of clinical practice. This population, therefore, provides a meaningful basis for comparing costs of follow-up mamm o g r a p h y with those of CNB, especially because the false-negative o u t c o m e rates of surveillance mammograp h y and CNB are comparable [1, 19, 21]. With use of published n u m b e r s from Medicare and RVP scales, the ratio of savings with surveillance m a m m o g r a p h y instead of CNB for probably benign lesions is approximately 8:1. This analysis should not be affected substantially by the k n o w n variability of Medicare and RVP scales in different areas of the country because the same Medicare and RVP scales are used as a basis for comparison of b o t h surveillance m a m m o g r a p h y and CNB and because the ratios of Medicare and RVP costs (not absolute dollar amounts) for rate of reimbursement of surveillance versus CNB are similar. Note that the cost of CNB will be slightly higher for those institutions that choose to p e r f o r m a single, unilateral, 6-month follow-up m a m m o g r a p h i c examination following benign core biopsy [31]. Our analysis provides a basis for understanding the difference in m a n a g e m e n t costs b e t w e e n surveillance m a m m o g r a p h y and CNB for probably benign lesions. Although CNB has b e e n s h o w n to be less expensive than surgical biopsy for lesions requiring tissue diagnosis, it is considerably m o r e expensive than surveillance m a m m o g r a p h y for probably benign lesions. The costsavings ratio is sensitive to reimbursement scales, showing a greater savings with the lower reimbursem e n t scales used for Medicare (7.4:1) than for RVP
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AND SICKLES
(6.8:1): The cost-savings ratio is even more sensitive in a negative manner to the use of CNB, showing a decrease to 5.6:1 if twice as many lesions in this studied population were subject to CNB, with no demonstrable change in o u t c o m e because the additional lesions sampled for biopsy would be benign. The low yield of malignancy (especially w h e n less than 20%) from many CNB series suggests that the ready availability of this technology may p r o m p t management by means of tissue diagnosis, although surveillance may be an equally accurate and m u c h less costly approach [1-4, 15-17]. Large prospective mammographic studies indicate a yield of malignancy of 38%47% w h e n tissue diagnosis is obtained only for those lesions that are truly suspicious for malignancy (ie, ACR BI-RADS categories 4 and 5) [14]. Because clinical outcomes for both approaches appear to be similar, cost factors b e c o m e increasingly important w h e n management strategies are being devised, especially in an era of managed care and strict utilization review [6, 10, 19211. The effect of delayed diagnosis of a mammographically detected lesion that is eventually s h o w n to be malignant is difficult to determine in any given case. However, becanse false-negative rates from published studies of surveillance, CNB, and surgical biopsy are similar, the effect is likely to be similar for all three approaches. Data from a national malpractice study concerning delayed diagnosis of breast cancer indicate substantial plaintiff awards for delays of 6 months to 1 year, but these data involved a majority of patients with clinical signs or symptoms of cancer [32]. These circumstances are different from those involving asymptomatic patients with mammographically detected lesions that are probably benign. Reported data suggest that probably benign lesions that have been followed up and eventually s h o w n to be cancer have a (favorable) prognosis similar to that of screening-detected cancers [14]. Indeed, unpublished follow-up data from the studied population reported herein demonstrate that all patients w h o were placed into surveillance but were later found to have cancer are alive and disease-free 120 months after the initial detection (E.A.S., unpublished data, 1997). At least one appellate court has dismissed claims for damages of a benign-appearing mammographic mass that grew from 3 to 9 m m in diameter before a malignant diagnosis was established; the patient showed no evidence of axillary node involvement or other spread of disease [33].
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We have not examined the comparative costs of USguided CNB and surveillance m a m m o g r a p h y because, to our knowledge, there are no published data about the subject. In addition, different protocols involving CNB may include short-term follow-up mammography; this would add to the cost of the procedure but has not been considered here because of the inconsistency with w h i c h this approach is used [9]. Although the cost of CNB has a positive economic effect (reduced cost) on the diagnosis of malignancy compared with excisional biopsy, w e have shown that the procedure has a substantially negative economic effect in the treatment of patients with probably benign breast lesions detected with screening mammography. This negative effect is accentuated by the lower reimbursement scales used by Medicare compared with RVP values, and it is even more dependent on the frequency with w h i c h CNB is used in a population of patients with lesions that have a very low likelihood of malignancy. REFERENCES 1. Parker SH, Lovin JD, Jobe WE, et al. Nonpalpable breast lesions: stereotactic automated large-core biopsies. Radiology 1991 ;180:403-407. 2. Dowlatshahi K, Yaremko ML, Kluskens LF, et al. Nonpalpable breast lesions: findings of stereotaxic needle core biopsy and fine-needle aspiration cytology. Radiology 1991 ;181:745-750. 3. Dronkers DJ. Stereotaxic core biopsy of breast lesions. Radiology 1992; 183:631-634. 4. Elvecrog EL, Lechner MC, Nelson MT. Nonpalpable breast lesions: correlation of stereotaxic large-core needle biopsy and surgical biopsy results. Radiology 1993; 188:453-455. 5. Sullivan DC. Needle core biopsy of mammographic lesions. A JR 1994; 162:601-608. 6. Parker SH, Burbank F, Jackman RJ, et al. Percutaneous large-core breast biopsy: a multi-institutional study. Radiology1994;193:359-364. 7. Caines JS, McPhee MD, Konok GP, et ai. Stereotaxic needle core biopsy of breast lesions using a regular mammographic table with an adaptable stereotaxic device. AJR 1994; 163:317-321. 8. Jackman RJ, Newels KW, Shepard MJ, et ai. Stereotaxic large-core needle biopsy of 450 nonpalpable breast lesions with surgical correlation in lesions with cancer or atypical hyperplasia. Radiology1994; 193:91-95. 9. Doyle A J, Murray KA, Nelson EW, et al. Selective use of image-guided large-core needle biopsy of the breast: accuracy and cost-effectiveness. AJR 1995; 165:281-284. 10. Brenner RJ, Fajardo L, Fisher PR, et ai. Percutaneous core biopsy of the breast: effect of operator experience and number of samples on diagnostic accuracy. AJR 1996; 166:341-346. 11. Caines JS, Chantziantoniou K, Wright BA, et al. Nova Scotia breast screening program experience: use of needle core biopsy in the diagnosis of screening-detected abnormalities. Radiology 1996; 198:125130. 12. Brenner RJ. Interventional procedures of the breast: medicolegal considerations. Radiology 1995; 195:611-615. 13. Liberman L, Fahs MC, Dershaw DD, et al. Impact of stereotaxic core breast biopsy on cost of diagnosis. Radiology1995;195:633-637. 14. Sickles EA. Management of probably benign breast lesions. Radiol Clin North Am 1996;33:1123-1130. 15. Janes RH, Bouton MS. Initial 300 consecutive stereotactic core-needle breast biopsies by a surgical group. Am J Surg 1994; 168:533-537.
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16. Mikhail RA, Nathan RC, Weiss M, et al. Stereotactic core needle biopsy of mammographic breast lesions as a viable alternative to surgical biopsy. Ann Surg Oncol 1994;1:363-367. 17. Israel PZ, Fine RE. Stereotactic needle biopsy for occult breast lesions: a minimally invasive alternative. Am Surg 1996;61:87-91. 18. Brenner RJ, Sickles EA. Acceptability of periodic follow-up as an alternative to biopsy for mammographically detected lesions interpreted as probably benign. Radiology1989;171:645-646. 19. Sickles EA. Periodic mammographic follow-up of probably benign lesions: results in 3,184 consecutive cases. Radiology 1991 ;179:463468. 20. Varas X, Leborgne F, Leborgne JH. Nonpalpable, probably benign lesions: role of follow-up mammography. Radiology 1992; 184:409-414. 21. Homer MJ. Pre-biopsy needle localization: methods, problems and expected results. Radiol Clin North Am 1992;30:139-153. 22. Lindfors KK, Rosenquist CJ. Needle core biopsy guided with mammography: a study of cost-effectiveness. Radiology 1994;190:217-222. 23. Sickles EA, Parker SH. Appropriate role of core breast biopsy in the management of probably benign lesions. Radiology 1993; 188:315. 24. Hillner BE, Bear HD, Fajardo LL. Estimating the cost-effectiveness of stereotaxic biopsy for nonpalpable breast abnormalities: a decision analysis model. Acad Radio11996;3:351-360. 25. Russell LB, Gold MR, Spiegel JE, et al. The role of cost-effectiveness analysis in health and medicine. JAMA 1996;276:1172-1177.
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Announcement The Office of Continuing Medical Education of the University of Michigan Medical School is sponsoring a conference entitled " 1 9 t h A n n u a l S e m i n a r i n D i a g n o s t i c U l t r a s o u n d " September 11-12, 1997, at the Towsley Center, University of Michigan Medical Center, Ann Arbor, MI. The course will review currently used techniques and applications of diagnostic ultrasound and emphasize n e w information and advances in this field, especially fetal imaging, obstetrics applications, D o p p l e r technique, and color flow imaging. Fifteen credit hours in category 1 of the Physician's Recognition Award of the American Medical Association will be available. (Other credits by specialty may apply.) The course director is Terry M. Silver, MD. For m o r e information, contact the registrar, Towsley Center for Continuing Medical Education, Department of Postgraduate Medicine and Health Care Professions, University of Michigan Medical School, PO Box 1157, Ann Arbor, MI 48106-1157; (313) 763-1400.
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