Abstract P2-01-20: The ratio and size of positive sentinel lymph nodes predicts the involvement of non-sentinel lymph nodes following completion axillary lymph node dissection

Background: The role of Completion Axillary Lymph Node Dissection (CALND) following positive Sentinel Lymph Node Biopsy (SLNB) is being actively debated. The involvement of our unit in the POSNOC trial (which has a no-treatment arm), has prompted a review of our unit’s CALND results, in order to examine predictors of involvement of non-sentinel lymph nodes (n-SLN), to better inform our patients during recruitment. Methods: We retrospectively analysed our experience of SNLB between July 2008 to 2013. A total of 1152 breast cancer patients underwent SLNB based on lymphoscintigraphy, intraoperative gamma probe detection, and blue dye mapping using 99mTc-nanocolloid and Patent Blue V injected peri-areola. Results: Out of 1152 SLN biopsies performed, 224 were positive for metastatic disease. 203 patients were anaesthetically capable of progressing to CALND. On univariate analysis, involved n-SLN on CALND could not be predicted by age ( 2; 3/7, p=0.213), receptor status; ER (negative; 3/13, positive 45/187, p=0.619), PR (negative; 6/28, positive 41/169, p=0.478), Her2 (negative; 43/175, positive 5/25, p=0.414), triple negative (2/8 vs 46/192, p=0.612). There was a trend toward higher incidence of positive n-SLN with increasing grade (G0-2; 28/139 vs G3; 20/64, p=0.062) and extracapsular spread (14/41 vs 32/149, p=0.073), but these did not reach statistical significance. Positive n-SLN on CALND was however predicted by macrometastases in SLN (macrometastases; 39/141 vs micrometastases; 9/62, p=0.029) and ratio of positive nodes ( Conclusion In our series of more than 200 SLNB, a ratio of >0.5 positive SLN yield and presence of macrometastases in positive SLN, were associated with positive n-SLN on CALND. Citation Format: Rajiv V Dave, Muhhamed N Chauhan, Maria Ghaus, Sana Ahmed, Shiv Shapra, Joshua Marriott, Craig Sayers, Zbigniew Kryjak, Deedar Ali. The ratio and size of positive sentinel lymph nodes predicts the involvement of non-sentinel lymph nodes following completion axillary lymph node dissection [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-01-20.