- Email: [email protected]
Accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer
The American Journal of Surgery 192 (2006) 516 –519
Presentation
Accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer Matthew S. Pugliese, M.D.a, Jennifer R. Kohr, M.D.a, Kimberly H. Allison, M.D.c, Nan Ping Wang, M.D., Ph.D.b, Ronald J. Tickman, M.D.b, J. David Beatty, M.D.a,* a
Department of Surgery, Comprehensive Breast Cancer Program, Swedish Cancer Institute, Seattle, WA, USA Department of Pathology, Comprehensive Breast Cancer Program, Swedish Cancer Institute, Seattle, WA, USA c Department of Anatomic Pathology, University of Washington Medical Center, 1959 NE Pacific, Seattle, WA 98122, USA b
Manuscript received April 5, 2006; revised manuscript May 31, 2006 Presented at the 7th Annual Meeting of the American Society of Breast Surgeons, Baltimore, Maryland, April 5–9, 2006
Abstract Background: In breast cancer treatment, immediate completion of axillary lymph node dissection (ALND) can be performed if the intraoperative sentinel lymph node (SLN) examination is positive. This study evaluates the accuracy of intraoperative imprint cytology (IC) for detecting SLN metastases. Methods: Pathology reports from 385 SLN biopsy examinations were reviewed retrospectively. The SLNs were serially sectioned perpendicular to the long axis and IC was performed intraoperatively. The SLNs then were formalin-fixed for permanent sections. Final pathology was compared with the intraoperative IC results. Results: The sensitivities for IC detection of N0(i⫹) (n ⫽ 36), N1mi (n ⫽ 24), and N1a-3a (n ⫽ 65) metastases were 0%, 4%, and 74%, respectively. The specificity was 100%. Conclusions: Final pathology identified 89 (23%) patients with N1 or greater disease. IC allowed 49 (55%) of these patients to undergo synchronous completion of ALND. No unnecessary completion ALNDs were performed. The sensitivity of IC decreased with decreasing size of the metastasis. © 2006 Excerpta Medica Inc. All rights reserved. Keywords: Imprint cytology; Touch preparation; Sentinel lymph node; Sentinel lymph node biopsy; Breast cancer
The accurate identification of axillary lymph node metastases is an important element in clinical decision making for patients with breast cancer. Axillary lymph node status provides prognostic information and is used to guide decisions involving adjuvant therapy. Surgical removal of positive axillary lymph nodes also is thought to facilitate local/ regional control. Complete level I and II axillary lymph node dissection (ALND) has been the standard way of obtaining this information. However, historically, many routine ALNDs were negative for metastatic disease. Given the high incidence of lymphedema after ALND, lymphatic mapping and sentinel lymph node (SLN) biopsy examination were introduced to help avoid the morbidity associated with routine ALND. Studies have shown that the incidence of lymphedema after SLN biopsy examination for breast * Corresponding author. Tel.: ⫹1-206-215-6410; fax: ⫹1-206-2156401. E-mail address: [email protected]
cancer treatment is much lower than the incidence of lymphedema after ALND [1,2]. Over the past decade, more surgeons have become comfortable with lymphatic mapping and SLN biopsy examination. An initial ALND still is recommended for patients who have clinically or pathologically documented axillary metastases. However, patients with early stage breast cancer without evidence of axillary disease are candidates for SLN biopsy examination. A positive SLN biopsy examination identifies a patient at risk of harboring additional axillary metastases. A completion ALND is recommended for these patients. Completion ALND can be performed as a synchronous procedure after SLN biopsy examination or as a second, delayed surgery. A synchronous surgery often is preferred because it can avoid the additional morbidity, cost, inconvenience, and psychologic impact of a second procedure. Both frozen section and imprint cytology (IC) are techniques used for the intraoperative evaluation of SLNs. Al-
0002-9610/06/$ – see front matter © 2006 Excerpta Medica Inc. All rights reserved. doi:10.1016/j.amjsurg.2006.05.014
M.S. Pugliese et al. / The American Journal of Surgery 192 (2006) 516 –519
517
Table 1 Accuracy of intraoperative IC compared with size of lymph node metastasis Final pathology (size)
Patients
Total patients, %
IC positive
IC negative
Sensitivity, %
Specificity, %
N0(i⫺) N0(i⫹) (ⱕ.2 mm) N1mi (⬎.2 mm, ⱕ2 mm) N1a–3a (⬎2 mm)
260 36 24 65
68 9 6 17
0 0 1 48
260 36 23 17
N/A 0 4 74
N/A 100 100 100
though prospective studies show frozen section and IC to have relatively equivalent sensitivities [3–5], several important differences do exist. Frozen section is a more common pathologic procedure for intraoperative assessment of the microscopic presence of tumor. The procedure is more time consuming, can be subject to freezing artifacts, and wastes a small amount of tissue when facing into the frozen tissue block. IC can be performed rapidly and does not waste tissue that may contain small metastases. A growing body of data is becoming available regarding the use of IC for SLN assessment intraoperatively, but the accuracy of this technique is still not yet characterized fully. Methods A retrospective review identified 385 consecutive patients with clinically node negative breast cancer who underwent SLN biopsy examination between June 2004 and July 2005. The pathology reports were reviewed. The intraoperative and final lymph node assessments were recorded and compared. None of the 385 patients were excluded for any reason. The study was submitted to and approved by this institution’s investigational review board. Sentinel nodes were identified using a combination of either isosulfan or methylene blue dye and technetium99m–labeled sulfur colloid. They were excised surgically and sent to pathology for intraoperative evaluation. Each sentinel node was serially sectioned at 1- to 2-mm intervals perpendicular to the long axis of the node. IC was performed on the cut surface of all nodal slices. The IC was examined microscopically and interpreted by a pathologist as positive or negative for metastatic disease. Indeterminate results were reported as atypical. The results were conveyed immediately to the surgeon. Atypical results were considered negative by the surgeon, pending final pathology. They also were considered negative for the purposes of this study. The sentinel nodes then were fixed in 10% buffered formalin and processed in the usual fashion for permanent sections. Ten sequential sections at an interval of 100 to 200 m between each level were collected from the tissue block of sentinel nodes. This ensured complete histologic examination of each 1- to 2-mm thick nodal slice. Section levels 2, 5, and 9 were evaluated by routine hematoxylin and eosin (H&E)-stained sections. If negative, section level 4 (or any additional level that was deemed appropriate) then was evaluated by immunohistochemical staining (IHC) for pankeratin. The lymph nodes were staged as N0(i-), N0(i⫹), N1mi, or N1a-3a according to the 6th edition of the American Joint Committee on Cancer Cancer Staging Manual and compared with the intraoperative IC results.
Results Intraoperative evaluation of SLNs was performed on 385 study patients, with a total of 1,013 SLNs (average, 2.67 lymph nodes/patient). Final pathologic examination using multiple H&E-stained levels and cytokeratin IHC identified axillary nodal metastases (N0[i⫹], N1mi, N1a-3a) in 165 nodes (16%) from 125 patients (32%). Isolated tumor cells or clusters of cells up to and including .2 mm in size (N0[i⫹]) were identified in 56 nodes (5%) from 36 patients (9%) on final pathology. Micrometastases, defined as clusters of metastatic cells greater than .2 mm, up to and including 2 mm (N1mi), were identified in 39 nodes (4%) from 24 patients (6%) on final pathology. Macrometastases, metastatic lesions greater than 2 mm in size (N1a-3a), were identified in 70 nodes (7%) from 65 patients (17%) on final pathology. The sensitivity for N0(i⫹), N1mi, and N1a-3a was 0%, 4%, and 74%, respectively. The specificity was 100%. These data are depicted in Table 1. The sensitivity of intraoperative IC on a per-patient basis for N1 disease (N1mi, N1a-3a) was 55%. The sensitivity of intraoperative IC on a per-patient basis for all patients with evidence of axillary metastases (N0[i⫹], N1mi, N1a-3a) was 39%. The positive and negative predictive values of intraoperative IC on a per-patient basis for N1 disease (N1mi, N1a-3a) were 100% and 87%, respectively. The positive and negative predictive values of intraoperative IC on a per-patient basis for all patients with evidence of axillary metastases (N0[i⫹], N1mi, N1a-3a) were 100% and 77%, respectively. Comments Accurate axillary staging has proven to be the strongest prognostic factor affecting women with early breast cancer [6,7]. This staging traditionally has been accomplished with a level I and II ALND. ALND provides necessary prognostic information and provides local control to patients with metastatic axillary disease. ALND should continue to be considered the standard, unless large prospective randomized studies such as the National Surgical Adjuvant and Bowel Project B-32 prove differently. However, as surgical techniques have evolved, an increasing number of patients and surgeons have elected to use SLN biopsy examination in hopes of avoiding the morbidity associated with a negative ALND. Multiple trials have documented that SLN biopsy examination reasonably reflects the stage of the axilla [8 –10]. However, the extent to which SLN biopsy examination provides local control is currently unknown. Therefore, completion ALND is indicated for patients with positive SLN biopsy specimens. SLNs can be assessed using a variety of techniques. Permanent sections with H&E staining are the standard
518
M.S. Pugliese et al. / The American Journal of Surgery 192 (2006) 516 –519
Table 2 Summary of the results from series evaluating the accuracy of IC for intraoperative assessment of SLNs in breast cancer Study
Year
Patients
Sensitivity
Specificity
False-positive results
Motamura et al [3] Kane et al [14] Shiver et al [15] Mullenix et al [16] Karamlou et al [17] Nagashima et al [18] Zgajnar et al [19] Ravichandran et al [20] Forbes et al [21] Pugliese
2000 2001 2002 2003 2003 2003 2004 2004 2005 2006
101 150 132 71 142 124 250 132 170 385
91% 54% 56% 48% 75% 70% 34% 70% 70% 55%*
98% 100% 100% 100% 100% 99% 99% 97% 96% 100%
2 0 0 0 0 1 2 Unknown 5 0
* Sensitivity includes all patients with N1 axillary status (N1mi, N1a–3a).
method of evaluation. In addition, intraoperative assessment of a SLN biopsy specimen can be performed by frozen section and/or IC. At our institution, IC is used routinely in the intraoperative evaluation of SLN. Frozen sections also are performed when the IC evaluation is suspicious but not diagnostic of metastases. The final postoperative SLN evaluation includes pankeratin IHC evaluation when the initial H&E levels are negative for metastatic disease. In this series, IHC evaluation of SLNs identified 39 patients with cytokeratin-positive malignant cell clusters less than .2 mm in size. These were not seen initially on H&E sections (N0[i⫹] disease). Controversy exists regarding the significance of this diagnosis [11,12]. However, the data tend to support the classification of these patients as N0 [13]. Both the National Surgical Adjuvant and Bowel Project B-32 and the American College of Surgeons Oncology Group’s Z0010 trial are expected to further clarify the significance of isolated tumor cells. Until additional data are available, the definition of a positive axillary lymph node will continue to be a subject of debate. All patients with positive IC results on a SLN had a synchronous ALND at the time of the SLN biopsy examination. Eighty-nine (23%) patients in our series had a final stage of N1 (N1mi, N1a-3a), and would be candidates for completion ALND. Intraoperative IC allowed 49 (55%) of the N1 or greater patients to benefit from synchronous ALND. Previous series examining the accuracy of intraoperative IC have reported sensitivities ranging from as low as 34% to as high as 96% [3,14 –21]. Table 2 shows a summary of our review of the English literature. Our series is large, but its sensitivity is less than the mean. However, there are no false positives and the population includes a large number of N0(i⫹) patients who may not have been detected previously. Several theories have attempted to explain the variation in reported sensitivity. Forbes et al [21] believed the most significant factor to be sampling error related to tumor burden. Tumor burden can vary significantly between populations at different institutions. At the Swedish Medical Center, patients undergoing ultrasound-guided tumor biopsy examination also have an ultrasound evaluation of the axilla. Any lymph nodes deemed suspicious by ultrasound undergo an ultrasound-guided fine-needle aspiration. If positive by fine-needle aspiration, the patient is offered an
initial ALND. This eliminates some high tumor burden lymph nodes from the series, decreasing sensitivity through selection bias. Many investigators have commented on the lower sensitivity of IC with micrometastatic disease. The sensitivity of IC in this series decreased significantly with decreasing size of the lesion, from 74% to 4% to 0% for N1a-3a to N1mi to N0(i⫹) lesions, respectively. This series further supports the theory that sensitivity for IC is related to tumor burden. However, tumor burden is only one part of sampling error. The sampled surface area also is significant. Increased sampled surface area is associated with an increased sensitivity of IC [22]. For this reason, each SLN in this series was sectioned at 1- to 2-mm intervals and all cut surfaces were evaluated with IC (Fig. 1). This technique is minimally more time consuming, but should facilitate synchronous completion ALND in the greatest number of patients, without compromising the accuracy of the final histologic assessment. Despite these steps, 17 of 65 patients (26%) with N1a-3a disease experienced a false-negative IC result. These falsenegative results are less likely related to sampling error. We
Fig. 1. Cluster of malignant cells in the center of normal-appearing lymphocytes on IC. Each sentinel node in the series was serially sectioned at 1- to 2-mm intervals perpendicular to the long axis. IC was performed on the cut surface of all nodal slices.
M.S. Pugliese et al. / The American Journal of Surgery 192 (2006) 516 –519
theorize that part of this false-negative rate is related to having a very high threshold for reporting a positive IC result. In this series, 19 (2%) lymph nodes were intraoperatively reported as atypical on IC evaluation. These lymph nodes were considered negative by the surgeon intraoperatively, pending the final pathology. They also were considered negative for the purposes of this study. On permanent sections, 4 patients (21%) were negative for metastatic disease N0(i-), 2 patients (11%) were N0(i⫹), 4 patients (21%) were N1mi, and 9 patients (47%) were N1a. If atypical intraoperative results were considered positive, the sensitivity for N0(i⫹), N1mi, and N1a-3a would increase to 6%, 21%, and 88%, respectively, with a decrease in specificity to 98%. We believe that a high threshold of positivity is important to avoid unnecessary synchronous ALNDs, even if this results in decreased sensitivity. Conclusions Intraoperative IC evaluation of sentinel nodes has adequate sensitivity and excellent specificity. The sensitivity was high (74%) for N1a-3a disease. However, the sensitivity of IC varied depending on the size of the SLN metastasis, decreasing to 4% for N1mi disease. Intraoperative IC allowed synchronous surgery in 49 (55%) patients in this series, reducing the rate of re-operation for complete ALND without causing unnecessary synchronous completion ALNDs. References [1] Morrell RM, Halyard MY, Schild SE, et al. Breast cancer-related lymphedema. Mayo Clin Proc 2005;80:1480 – 4. [2] Wilke LG, McCall LM, Posther KE, et al. Surgical complications associated with sentinel lymph node biopsy: results from a prospective international cooperative group trial. Ann Surg Oncol 2006;12: 491–500. [3] Motomura K, Inaji H, Komoike Y, et al. Intraoperative sentinel lymph node examination by imprint cytology and frozen sectioning during breast surgery. Br J Surg 2000;87:597– 601. [4] Diest PJ, Torrenga H, Borgstein PJ, et al. Reliability of intraoperative frozen section and imprint cytological investigation of sentinel lymph nodes in breast cancer. Histopathology 1999;35:14 – 8. [5] Menes TS, Tartter PI, Mizrachi H, et al. Touch preparation or frozen section of sentinel lymph node metastases from breast cancer. Ann Surg Oncol 2003;10:1166 –70. [6] Fitzgibbons PL, Page DL, Weaver D, et al. Prognostic factors in breast cancer. College of American Pathologists Consensus Statement, 1999. Arch Pathol Lab Med 2000;124:966 –78.
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[7] Singletary SE, Alfred C, Ashley P, et al. Revision of the American Joint Committee on Cancer staging system for breast cancer. J Clin Oncol 2002;20:3628 –36. [8] Giuliano AE, Kirgan DM, Guenther JM, et al. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg 1994;220: 391– 8. [9] Albertini JJ, Lyman GH, Cox C, et al. Lymphatic mapping and sentinel node biopsy in the patient with breast cancer. JAMA 1996; 276:1818 –22. [10] Kelley MC, Hansen N, McMasters KM. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Am J Surg 2004;188: 49 – 61. [11] Nasser IA, Lee AK, Bosari S, et al. Occult axillary lymph node metastases in “node-negative” breast carcinoma. Hum Pathol 1993; 24:950 –7. [12] Susnik B, Frkovic-Grazio S, Bracko M. Occult micrometastases in axillary lymph nodes predict subsequent distant metastases in stage I breast cancer: a case-control study with 15-year follow-up. Ann Surg Oncol 2004;11:568 –72. [13] Singletary ES. Early-stage invasive breast cancer: isolated tumor cells in axillary lymph nodes, peripheral blood, and bone marrow. Gen Surg News 2006;33:17–20. [14] Kane JM III, Edge SB, Winston JS, et al. Intraoperative pathologic evaluation of a breast cancer sentinel lymph node biopsy as a determinant for synchronous axillary lymph node dissection. Ann Surg Oncol 2001;8:361–7. [15] Shiver SA, Creager AJ, Geisinger K, et al. Intraoperative analysis of sentinel lymph nodes by imprint cytology for cancer of the breast. Am J Surg 2002;184:424 –7. [16] Mullenix PS, Carter PL, Martin MJ, et al. Predictive value of intraoperative touch preparation analysis of sentinel lymph nodes for axillary metastasis in breast cancer. Am J Surg 2003;185:420 – 4. [17] Karamlou T, Johnson NM, Chan B, et al. Accuracy of intraoperative touch imprint cytologic analysis of sentinel lymph nodes in breast cancer. Am J Surg 2003;185:425– 8. [18] Nagashima T, Suzuki M, Yagata H, et al. Intraoperative cytologic diagnosis of sentinel node metastases in breast cancer. Acta Cytol 2003;47:1028 –32. [19] Zgajnar J, Frkovic-Grazio S, Besic N, et al. Low sensitivity of the touch imprint cytology of the sentinel lymph node in breast cancer patients—results of a large series. J Surg Oncol 2004;85:82– 6. [20] Ravichandran D, Kocjan G, Falzon M, et al. Imprint cytology of the sentinel lymph node in the assessment of axillary node status in breast carcinoma. Eur J Surg Oncol 2004;30:238 – 42. [21] Forbes RC, Pitchford C, Simpson JF, et al. Selective use of intraoperative touch prep analysis of sentinel nodes in breast cancer. Am Surg 2005;71:955– 60. [22] Cserni G. Effect of increasing the surface sampled by imprint cytology on the intraoperative assessment of axillary sentinel lymph nodes in breast cancer patients. Am Surg 2003;69:419 –23.
Presentation
Accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer Matthew S. Pugliese, M.D.a, Jennifer R. Kohr, M.D.a, Kimberly H. Allison, M.D.c, Nan Ping Wang, M.D., Ph.D.b, Ronald J. Tickman, M.D.b, J. David Beatty, M.D.a,* a
Department of Surgery, Comprehensive Breast Cancer Program, Swedish Cancer Institute, Seattle, WA, USA Department of Pathology, Comprehensive Breast Cancer Program, Swedish Cancer Institute, Seattle, WA, USA c Department of Anatomic Pathology, University of Washington Medical Center, 1959 NE Pacific, Seattle, WA 98122, USA b
Manuscript received April 5, 2006; revised manuscript May 31, 2006 Presented at the 7th Annual Meeting of the American Society of Breast Surgeons, Baltimore, Maryland, April 5–9, 2006
Abstract Background: In breast cancer treatment, immediate completion of axillary lymph node dissection (ALND) can be performed if the intraoperative sentinel lymph node (SLN) examination is positive. This study evaluates the accuracy of intraoperative imprint cytology (IC) for detecting SLN metastases. Methods: Pathology reports from 385 SLN biopsy examinations were reviewed retrospectively. The SLNs were serially sectioned perpendicular to the long axis and IC was performed intraoperatively. The SLNs then were formalin-fixed for permanent sections. Final pathology was compared with the intraoperative IC results. Results: The sensitivities for IC detection of N0(i⫹) (n ⫽ 36), N1mi (n ⫽ 24), and N1a-3a (n ⫽ 65) metastases were 0%, 4%, and 74%, respectively. The specificity was 100%. Conclusions: Final pathology identified 89 (23%) patients with N1 or greater disease. IC allowed 49 (55%) of these patients to undergo synchronous completion of ALND. No unnecessary completion ALNDs were performed. The sensitivity of IC decreased with decreasing size of the metastasis. © 2006 Excerpta Medica Inc. All rights reserved. Keywords: Imprint cytology; Touch preparation; Sentinel lymph node; Sentinel lymph node biopsy; Breast cancer
The accurate identification of axillary lymph node metastases is an important element in clinical decision making for patients with breast cancer. Axillary lymph node status provides prognostic information and is used to guide decisions involving adjuvant therapy. Surgical removal of positive axillary lymph nodes also is thought to facilitate local/ regional control. Complete level I and II axillary lymph node dissection (ALND) has been the standard way of obtaining this information. However, historically, many routine ALNDs were negative for metastatic disease. Given the high incidence of lymphedema after ALND, lymphatic mapping and sentinel lymph node (SLN) biopsy examination were introduced to help avoid the morbidity associated with routine ALND. Studies have shown that the incidence of lymphedema after SLN biopsy examination for breast * Corresponding author. Tel.: ⫹1-206-215-6410; fax: ⫹1-206-2156401. E-mail address: [email protected]
cancer treatment is much lower than the incidence of lymphedema after ALND [1,2]. Over the past decade, more surgeons have become comfortable with lymphatic mapping and SLN biopsy examination. An initial ALND still is recommended for patients who have clinically or pathologically documented axillary metastases. However, patients with early stage breast cancer without evidence of axillary disease are candidates for SLN biopsy examination. A positive SLN biopsy examination identifies a patient at risk of harboring additional axillary metastases. A completion ALND is recommended for these patients. Completion ALND can be performed as a synchronous procedure after SLN biopsy examination or as a second, delayed surgery. A synchronous surgery often is preferred because it can avoid the additional morbidity, cost, inconvenience, and psychologic impact of a second procedure. Both frozen section and imprint cytology (IC) are techniques used for the intraoperative evaluation of SLNs. Al-
0002-9610/06/$ – see front matter © 2006 Excerpta Medica Inc. All rights reserved. doi:10.1016/j.amjsurg.2006.05.014
M.S. Pugliese et al. / The American Journal of Surgery 192 (2006) 516 –519
517
Table 1 Accuracy of intraoperative IC compared with size of lymph node metastasis Final pathology (size)
Patients
Total patients, %
IC positive
IC negative
Sensitivity, %
Specificity, %
N0(i⫺) N0(i⫹) (ⱕ.2 mm) N1mi (⬎.2 mm, ⱕ2 mm) N1a–3a (⬎2 mm)
260 36 24 65
68 9 6 17
0 0 1 48
260 36 23 17
N/A 0 4 74
N/A 100 100 100
though prospective studies show frozen section and IC to have relatively equivalent sensitivities [3–5], several important differences do exist. Frozen section is a more common pathologic procedure for intraoperative assessment of the microscopic presence of tumor. The procedure is more time consuming, can be subject to freezing artifacts, and wastes a small amount of tissue when facing into the frozen tissue block. IC can be performed rapidly and does not waste tissue that may contain small metastases. A growing body of data is becoming available regarding the use of IC for SLN assessment intraoperatively, but the accuracy of this technique is still not yet characterized fully. Methods A retrospective review identified 385 consecutive patients with clinically node negative breast cancer who underwent SLN biopsy examination between June 2004 and July 2005. The pathology reports were reviewed. The intraoperative and final lymph node assessments were recorded and compared. None of the 385 patients were excluded for any reason. The study was submitted to and approved by this institution’s investigational review board. Sentinel nodes were identified using a combination of either isosulfan or methylene blue dye and technetium99m–labeled sulfur colloid. They were excised surgically and sent to pathology for intraoperative evaluation. Each sentinel node was serially sectioned at 1- to 2-mm intervals perpendicular to the long axis of the node. IC was performed on the cut surface of all nodal slices. The IC was examined microscopically and interpreted by a pathologist as positive or negative for metastatic disease. Indeterminate results were reported as atypical. The results were conveyed immediately to the surgeon. Atypical results were considered negative by the surgeon, pending final pathology. They also were considered negative for the purposes of this study. The sentinel nodes then were fixed in 10% buffered formalin and processed in the usual fashion for permanent sections. Ten sequential sections at an interval of 100 to 200 m between each level were collected from the tissue block of sentinel nodes. This ensured complete histologic examination of each 1- to 2-mm thick nodal slice. Section levels 2, 5, and 9 were evaluated by routine hematoxylin and eosin (H&E)-stained sections. If negative, section level 4 (or any additional level that was deemed appropriate) then was evaluated by immunohistochemical staining (IHC) for pankeratin. The lymph nodes were staged as N0(i-), N0(i⫹), N1mi, or N1a-3a according to the 6th edition of the American Joint Committee on Cancer Cancer Staging Manual and compared with the intraoperative IC results.
Results Intraoperative evaluation of SLNs was performed on 385 study patients, with a total of 1,013 SLNs (average, 2.67 lymph nodes/patient). Final pathologic examination using multiple H&E-stained levels and cytokeratin IHC identified axillary nodal metastases (N0[i⫹], N1mi, N1a-3a) in 165 nodes (16%) from 125 patients (32%). Isolated tumor cells or clusters of cells up to and including .2 mm in size (N0[i⫹]) were identified in 56 nodes (5%) from 36 patients (9%) on final pathology. Micrometastases, defined as clusters of metastatic cells greater than .2 mm, up to and including 2 mm (N1mi), were identified in 39 nodes (4%) from 24 patients (6%) on final pathology. Macrometastases, metastatic lesions greater than 2 mm in size (N1a-3a), were identified in 70 nodes (7%) from 65 patients (17%) on final pathology. The sensitivity for N0(i⫹), N1mi, and N1a-3a was 0%, 4%, and 74%, respectively. The specificity was 100%. These data are depicted in Table 1. The sensitivity of intraoperative IC on a per-patient basis for N1 disease (N1mi, N1a-3a) was 55%. The sensitivity of intraoperative IC on a per-patient basis for all patients with evidence of axillary metastases (N0[i⫹], N1mi, N1a-3a) was 39%. The positive and negative predictive values of intraoperative IC on a per-patient basis for N1 disease (N1mi, N1a-3a) were 100% and 87%, respectively. The positive and negative predictive values of intraoperative IC on a per-patient basis for all patients with evidence of axillary metastases (N0[i⫹], N1mi, N1a-3a) were 100% and 77%, respectively. Comments Accurate axillary staging has proven to be the strongest prognostic factor affecting women with early breast cancer [6,7]. This staging traditionally has been accomplished with a level I and II ALND. ALND provides necessary prognostic information and provides local control to patients with metastatic axillary disease. ALND should continue to be considered the standard, unless large prospective randomized studies such as the National Surgical Adjuvant and Bowel Project B-32 prove differently. However, as surgical techniques have evolved, an increasing number of patients and surgeons have elected to use SLN biopsy examination in hopes of avoiding the morbidity associated with a negative ALND. Multiple trials have documented that SLN biopsy examination reasonably reflects the stage of the axilla [8 –10]. However, the extent to which SLN biopsy examination provides local control is currently unknown. Therefore, completion ALND is indicated for patients with positive SLN biopsy specimens. SLNs can be assessed using a variety of techniques. Permanent sections with H&E staining are the standard
518
M.S. Pugliese et al. / The American Journal of Surgery 192 (2006) 516 –519
Table 2 Summary of the results from series evaluating the accuracy of IC for intraoperative assessment of SLNs in breast cancer Study
Year
Patients
Sensitivity
Specificity
False-positive results
Motamura et al [3] Kane et al [14] Shiver et al [15] Mullenix et al [16] Karamlou et al [17] Nagashima et al [18] Zgajnar et al [19] Ravichandran et al [20] Forbes et al [21] Pugliese
2000 2001 2002 2003 2003 2003 2004 2004 2005 2006
101 150 132 71 142 124 250 132 170 385
91% 54% 56% 48% 75% 70% 34% 70% 70% 55%*
98% 100% 100% 100% 100% 99% 99% 97% 96% 100%
2 0 0 0 0 1 2 Unknown 5 0
* Sensitivity includes all patients with N1 axillary status (N1mi, N1a–3a).
method of evaluation. In addition, intraoperative assessment of a SLN biopsy specimen can be performed by frozen section and/or IC. At our institution, IC is used routinely in the intraoperative evaluation of SLN. Frozen sections also are performed when the IC evaluation is suspicious but not diagnostic of metastases. The final postoperative SLN evaluation includes pankeratin IHC evaluation when the initial H&E levels are negative for metastatic disease. In this series, IHC evaluation of SLNs identified 39 patients with cytokeratin-positive malignant cell clusters less than .2 mm in size. These were not seen initially on H&E sections (N0[i⫹] disease). Controversy exists regarding the significance of this diagnosis [11,12]. However, the data tend to support the classification of these patients as N0 [13]. Both the National Surgical Adjuvant and Bowel Project B-32 and the American College of Surgeons Oncology Group’s Z0010 trial are expected to further clarify the significance of isolated tumor cells. Until additional data are available, the definition of a positive axillary lymph node will continue to be a subject of debate. All patients with positive IC results on a SLN had a synchronous ALND at the time of the SLN biopsy examination. Eighty-nine (23%) patients in our series had a final stage of N1 (N1mi, N1a-3a), and would be candidates for completion ALND. Intraoperative IC allowed 49 (55%) of the N1 or greater patients to benefit from synchronous ALND. Previous series examining the accuracy of intraoperative IC have reported sensitivities ranging from as low as 34% to as high as 96% [3,14 –21]. Table 2 shows a summary of our review of the English literature. Our series is large, but its sensitivity is less than the mean. However, there are no false positives and the population includes a large number of N0(i⫹) patients who may not have been detected previously. Several theories have attempted to explain the variation in reported sensitivity. Forbes et al [21] believed the most significant factor to be sampling error related to tumor burden. Tumor burden can vary significantly between populations at different institutions. At the Swedish Medical Center, patients undergoing ultrasound-guided tumor biopsy examination also have an ultrasound evaluation of the axilla. Any lymph nodes deemed suspicious by ultrasound undergo an ultrasound-guided fine-needle aspiration. If positive by fine-needle aspiration, the patient is offered an
initial ALND. This eliminates some high tumor burden lymph nodes from the series, decreasing sensitivity through selection bias. Many investigators have commented on the lower sensitivity of IC with micrometastatic disease. The sensitivity of IC in this series decreased significantly with decreasing size of the lesion, from 74% to 4% to 0% for N1a-3a to N1mi to N0(i⫹) lesions, respectively. This series further supports the theory that sensitivity for IC is related to tumor burden. However, tumor burden is only one part of sampling error. The sampled surface area also is significant. Increased sampled surface area is associated with an increased sensitivity of IC [22]. For this reason, each SLN in this series was sectioned at 1- to 2-mm intervals and all cut surfaces were evaluated with IC (Fig. 1). This technique is minimally more time consuming, but should facilitate synchronous completion ALND in the greatest number of patients, without compromising the accuracy of the final histologic assessment. Despite these steps, 17 of 65 patients (26%) with N1a-3a disease experienced a false-negative IC result. These falsenegative results are less likely related to sampling error. We
Fig. 1. Cluster of malignant cells in the center of normal-appearing lymphocytes on IC. Each sentinel node in the series was serially sectioned at 1- to 2-mm intervals perpendicular to the long axis. IC was performed on the cut surface of all nodal slices.
M.S. Pugliese et al. / The American Journal of Surgery 192 (2006) 516 –519
theorize that part of this false-negative rate is related to having a very high threshold for reporting a positive IC result. In this series, 19 (2%) lymph nodes were intraoperatively reported as atypical on IC evaluation. These lymph nodes were considered negative by the surgeon intraoperatively, pending the final pathology. They also were considered negative for the purposes of this study. On permanent sections, 4 patients (21%) were negative for metastatic disease N0(i-), 2 patients (11%) were N0(i⫹), 4 patients (21%) were N1mi, and 9 patients (47%) were N1a. If atypical intraoperative results were considered positive, the sensitivity for N0(i⫹), N1mi, and N1a-3a would increase to 6%, 21%, and 88%, respectively, with a decrease in specificity to 98%. We believe that a high threshold of positivity is important to avoid unnecessary synchronous ALNDs, even if this results in decreased sensitivity. Conclusions Intraoperative IC evaluation of sentinel nodes has adequate sensitivity and excellent specificity. The sensitivity was high (74%) for N1a-3a disease. However, the sensitivity of IC varied depending on the size of the SLN metastasis, decreasing to 4% for N1mi disease. Intraoperative IC allowed synchronous surgery in 49 (55%) patients in this series, reducing the rate of re-operation for complete ALND without causing unnecessary synchronous completion ALNDs. References [1] Morrell RM, Halyard MY, Schild SE, et al. Breast cancer-related lymphedema. Mayo Clin Proc 2005;80:1480 – 4. [2] Wilke LG, McCall LM, Posther KE, et al. Surgical complications associated with sentinel lymph node biopsy: results from a prospective international cooperative group trial. Ann Surg Oncol 2006;12: 491–500. [3] Motomura K, Inaji H, Komoike Y, et al. Intraoperative sentinel lymph node examination by imprint cytology and frozen sectioning during breast surgery. Br J Surg 2000;87:597– 601. [4] Diest PJ, Torrenga H, Borgstein PJ, et al. Reliability of intraoperative frozen section and imprint cytological investigation of sentinel lymph nodes in breast cancer. Histopathology 1999;35:14 – 8. [5] Menes TS, Tartter PI, Mizrachi H, et al. Touch preparation or frozen section of sentinel lymph node metastases from breast cancer. Ann Surg Oncol 2003;10:1166 –70. [6] Fitzgibbons PL, Page DL, Weaver D, et al. Prognostic factors in breast cancer. College of American Pathologists Consensus Statement, 1999. Arch Pathol Lab Med 2000;124:966 –78.
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