Cost-effectiveness of stereotaxic breast core needle biopsy

Cost-Effectiveness and Outcome Studies: E x a m p l e s of Research

Cost-Effectiveness of Stereotaxic Breast Core Needle Biopsy Laurie L. Fajardo, MD

arrying out cost-effectiveness analyses has b e c o m e increasingly popular in the economic evaluation of health care technologies for many subspecialties of medicine. During the past 20 years, however, a recurring pattern of new imaging technologies disseminating rapidly into routine use without controlled, scientific studies has emerged. The use of stereotaxic breast needle biopsy (SBNB) to replace surgical excision biopsy (SEB) is a recent example of this phenomenon. Implicitly, cost-effectiveness researchers acknowledge that resources are not sufficient for physicians to spend all they would like on health care and seek to provide the information necessary for society to set priorities for use of the funds that are available. As a result, health care providers may increasingly consider technologies that are significantly less costly, but perhaps slightly less effective than a competing alternative. Stereotaxic breast needle biopsy, although heady comparable to surgical excisional biopsy under ideal practice conditions, may fall into this category. The pertinent question becomes, then, To what degree will radiologists accept a reduction in efficacy to achieve a certain reduction in cost? In other words, if one is willing to save Xamount of dollars per delayed (or missed) breast cancer diagnosis, then the most costeffective strategy is K Proponents of SBNB over SEB are likely to find it necessary to address the concept of decremental cost-effectiveness analysis. Considered in isolation, the performance of SEB over time has been generally excellent, with specificity and sensitivity both approaching 90-100% (i.e., no false-positive and few false-negative histologic outcomes). Unfortunately, the decision to evaluate impalpable breast lesions is driven by mammography, a technology with lower sensitivity. Thus, the outcome of a majority (70-90%) of SEBs is negative, and the concept of "unnecessary breast surgery" has arisen. Because SBNB can be performed less expensively, less invasively, with local anesthesia only, and with better cosmesis, it has been used more and more frequently in the past 5 years. Comparisons of SEB and SBNB thus far, however, can be criticized because the majority have evaluated fewer than 100 patients [1-9]. In reports using larger populations, most patients have not undergone SEB to confirm pathologic findings, and sufficient mammographic follow-up (i.e., at least 2 years) has not been done in patients not undergoing surgery.

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From the Department of Radiology, University of Virginia, Charlottesville, VA. Adclress reprint requests to L. L. Fajardo, MD, Department of Radiology, University of Virginia Health Science Center, Box 170, Charlottesville, VA 22908. Acad Radiol 1996;3:S21-S23 9 1996, Association of University Radiologists

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FAJARDO

The results discussed here are from a study group of 400 patients evaluated with SBNB. The specific aims of this trial were to evaluate the efficacy of SBNB for the primary management of impalpable breast lesions and to determine whether SBNB is a cost-effective substitute for SEB. MATERIALS AND METHODS

Four hundred patients with impalpable (mammographic) breast lesions were enrolled prospectively into the study. For each lesion, a mammographic characterization was made, according to the American College of Radiology lexicon, and a mammographic suspicion was assigned [3]. For each lesion, at least five stereotaxic core needle (14-gauge) biopsies were done. Core biopsy material was routinely processed and evaluated by using the following determinants: (1) insufficient samRle; (2) negative, nonspecific benign, or specific benign! lesion (e.g., fibroadenoma); (3) hyperplasia with atypia (or other "premalignant" lesion); (4) ductal carcinoma ifi situ (DCIS); and (5) invasive carcinoma. The results of core needle biopsy were correlated with the prebiopsy mammographic characterization. Patients were managed according to the following protocols. 1. Nonsurgical pat!ents (those with a probably benign or indeterminate mammographic lesion whose core biopsy results were negative, specific benign, or benign lesions without atypia) underwent mammographic follow-up at 6, 12, and 24 months after the negative SBNB. 2. Patients with any mammographic diagnosis having insufficient or inadequate core biopsy material underwent immediate repeat evaluation, either by SBNB or SEB. 3. Likewise, patients with suspicious or malignantappearing lesions by mammography having a negative or nonspecific benign SBNB result underwent immediate reevaluation by either repeat SBNB or SEB. 4. Patients with any mammographic diagnosis having DCIS on SBNB underwent an outpatient lumpectomy under local anesthesia with intravenous sedation. If tile surgical specimens showed evidence of invasive carcinoma, a second surgical procedure was done to stage the axillary lymph nodes. 5. Patients with invasive carcinoma on SBNB were managed with the definitive, therapeutic procedure of choice, either mastectomy or lumpectomy, with axillary lymph n o d e dissection. RESULTS Management Outcomes and Results

A total of 129 patients underwent surgical procedures. Of these, 94 patients had cancer and 35 had $22

rot. 3, Suppl. 1, April 1996

benign disease. The overall positive predictive value for tile group undergoing SEB after SBNB was 24%. Twelve patients with indetermir~ate or suspicious mammographic findings had immediate reevaluations after inadequate SBNB or negative, nonspecific benign SBNB results. Five of the 12 had repeat SBNB, and of these, three had cancer, whereas the other two had benign lesions. The latter two patients were subsequently managed in the follow-up arm and showed no change on mammograms during the follow-up period of 2 years. Seven of the 12 patients were reevaluated with SEB. In these seven patients, two surgical specimens were malignant and five were benign. A total of 271 patients were in the follow-up group. One hundred ninety-one patients underwent all three recommended follow-up mammographic examinations; 13 patients had none of the recommended follow-up studies. Eleven patients, with initial negative results of SBNB, showed untoward interval changes (i.e., increase in size, number of microcalcifications, or mammographic suspicion) on their follow-up mammograms. Four of these were identified on tile 6-month follow-up mammogram, and seven were identified on the 12-month follow-up mammogram. No untoward interval Cllanges were detected on the 24-month follow-up studies. When tile 11 lesions were reevaluated by SEB or SBNB, eight were found to be benign and three were malignant. The eight benign lesions included four fibroadenomas that grew, three benign groups of microealcifications (wifllout atypia) that increased in number, and one nonspecific benign mass (apocrine metaplasia). All three of tile malignant lesions were stage I ductal carcinomas and had negative lymph nodes. Two of the lesions were less than 1 cm in size, and the third was 1.8 cm in size. The malignant diagnoses were made at 6, 8, and 13 months after negative SBNB. With the inadequate and indeterminate biopsies included in tile denominator of the appropriate equation, the overall sensitivity and specificity for SBNB in this study were .91 and .98, respectively. Cost-Efficacy Analysis

For the cost-efficacy analysis, a societal perspective was assumed and the following end points were examined: (1) disease diagnosed by SBNB (DCIS or invasive breast cancer); (2) delayed diagnosis for 6-12 months; (3) missed diagnosis; (3) cost; and (4) "unnecessary" surgery (negative SEB results). I also assumed a base case probability of cancer for patients undergoing SBNB to be 10~ for both DCIS and invasive cancer. Furthermore, I used cost-to-charge ratios

COST-EFFECTIVENESS OF BREAST NEEDLE BIOPSY

Vol. 3, Suppl. 1, April 1996 FIGURE 1. Derision tree for cost-effectiveness

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for a single institution (tile University of Virginia) tO determine that t!m average cost of SBNB and mammographic followup for patients with negative SBNB results was 40% of the.cost of SEB. The cost of outpatient SEB was calculated at $1,500. When calculating the cost for patients requiring a second SBNB or SEB for inadequate initial biopsies or discordance with the manmlographic findings (i.e., suspicious mammographic findings with negative or nonspecific benign findings at SBNB), I used the cost of SEB for all cases. I further assumed that outpatient SEB would suffice as a definitive lumpectomy for patients having DCIS (i.e., the SEB would have negative surgical margins and reexcision would not be necessary). These assumptions were conservative and were biased in favor of SEB. A furtlier assumption was that if delayed diagnoses by SBNB were stage I with negative lymph nodes, then treatment costs for cancers diagnosed by SBNB versus SEB would not differ. If this were to hold true universally, then downstream treatment costs can be ignored. If not, the incremental cost of a delayed diagnosis versus immediate treatment becomes relevant. Tile decision tree for the cost analysis is shown in Figure 1. Using the assumptions just described, I found the following financial trade-offs for SBNB versus SEB: 1. SEB costs on average $645 more per woman. 2. SEB costs an additional $86,000 per additional stage I invasive cancer detected (or, otherwise stated, SBNB saves $86,000 per delayed breast cancer diagnosis). DISCUSSION

' Ahhough tile results of this study highlights both clinical and economic advantages of SBNB, the study was not a complete evaluation of the ahernatives available. Limitations and uncertainties in this analysis include (1) the uncertainty related to tile exact probability of DCIS

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and invasive carcinoma in a broad population of w o m e n w h o would be considered eligible for diagnosis using SBNB, (2) limited controlled-trial data on the test characteristics of SBNB, (3) limitations in deriving true costs for SEB and SBNB, and (4) uncertainty related to the prognostic significance of a 6- to 12-month delay in diagnosis of an early breast cancer. A randomized trial, the Radiologic Diagnostic Oncology Group 5 Trial, is currently in progress. In tliat study, 3,600 women will be randomized into groups to undergo breast needle biopsy by either fine versus core needle, and with stereotaxic versus sonogmphic iinaging guidance. When this randomized, controlled trial is completed, the test characteristics for SBNB will be more thoroughly defined. In tile meantime, the work reported here gives dimensions to tile patient and financial tmdeoffs of using SBNB in lieu of surgical biopsy. REFERENCES 1. Evans WP, Cade SH. Needle localization and fine-needle aspiration biopsy of nonpalpable breast lesions with use of standard and stereotactic equipment. Radiology 1989;170:53-56. 2. Dowlatshahi K, Gent H, Schmidt R, Jokich P, Bibbo M, Sprenger E. NonpaTpable breast tumor: diagnosis with stereotactic localization and fineneedle aspiration. Radiology 1989;170:427-433. 3. Fajardo LL, Davis JR, Wiens JL, Trego DC. Mammography-guidedsteieotactic fine-needle as#ration cytology of nonpaipabte bre~ist lesions: prospective comparison with surgical biopsy results. AJR 1990;155:977-981. 4. Parker SH, Lovin JD, Jobe WE, et aL Stereotactic breast biopsy with a biopsy gun. Radiology 199{);176:741-747. 5. Jackson VP, Reynolds HE. Stereotaxic needle-c-orebiopsy and fine-needie aspiration cytologic evaluation of nonpalpable breast lesions. Radiology 1991;181:633-634. 6. Dowlatshahi K, Yaremko ML, Kluskens LF, Jokich PM. Nonpalpable breast lesions: findings of Stereotaxic needle-core biopsy and fine-needle aspiration cytology. Radiology 1991; 181:745-750. 7. Dronkers D. Stereotactic core biopsy of breast lesions. Radiology 1992; 183:631-634. 8. Elliot RL, Haynes AE, Bolin JA, Boagni EM, Head JF. Stereotactic needie localization and biopsy of occult breast lesions: first year's experience. Am J Surg 1992;58:126-131. 9. Parker SH, Burbank F, Jaokman RJ, et al. Percutaneous large-core breast biopsy: a rnulti-institutional study. Radiology 1994;193:359-364.

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