[306] A Single Institution Analysis of Metastatic Breast Carcinoma and Axillary Sentinel Lymph Node False-Negative Intraoperative Interpretations over a Ten Year Period

Darryl Yu, Sveta Silverman, John Danyluk. Misericordia Hospital, Edmonton, AB, Canada; University of Alberta, Edmonton, AB, Canada

Background: We evaluated 1720 cases of breast carcinomas excised with axillary sentinel lymph nodes from 2000-2010 to determine the diagnostic accuracy of sentinel node intraoperative scrape preparations. The false-negative intraoperative interpretations were analyzed in relation to the size and location of metastatic deposits on permanent sections, and the characteristics of the underlying primary tumor. In addition, the node status was determined in patients who underwent subsequent axillary node dissection following a false-negative intraoperative interpretation.
Design: 1720 breast carcinomas excised with axillary sentinel lymph nodes and some with axillary contents in the period between 2000-2010 were reviewed. All sentinel node intraoperative scrape preparation interpretations were compared to the formalin fixed, paraffin embedded permanent sections to determine diagnostic accuracy using standard calculations. Sentinel lymph node false-negative intraoperative interpretations was analyzed with regard to the size, location of metastatic deposits, primary tumor histologic subtype, size, grade, lymphovascular invasion, and node status following subsequent axillary lymph node dissection.
Results: 109 false negative results were identified on permanent sections (32 macrometastasis and 77). Of the macrometastasis there were 21 (66%) ductal, 10 (31%) lobular, and 1 ductolobular carcinomas. Of the micrometastasis there were 63 (82%) ductal, 10 (13%) lobular, 2 ductolobular, and 2 mucinous carcinomas. 73 patients with false-negative intraoperative interpretations underwent subsequent axillary lymph node dissection with 7/73 patients having metastatic carcinoma (5 ductal, 1 ductolobular, 1 lobular carcinomas) in the axillary lymph nodes on permanent sections.
Conclusions: The sensitivity of the intraoperative scrape preparation was 71.3% and the specificity was 99.5%. The positive predictive value was 0.98 and the negative predictive value was 0.91. Micrometastases (71%) accounted for most of the false-negatives intraoperative interpretations. Overall, invasive ductal carcinoma was the predominant subtype within all false-negative sentinel lymph nodes. Macrometastases had a higher proportion of lobular carcinomas than micrometastases. Only a small number (10%) of patients with false-negative interpretations at intraoperative scrape preparation ultimately had metastatic carcinoma in their axillary nodes following a subsequent axillary lymph node dissection.
Category: Breast

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 17, Wednesday Morning


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