P3-07-17: Optimal Number of Sentinel Lymph Nodes That Could Avoid Completion of Axillary Lymph Node Dissection in Operable Breast Cancer.

Abstract

Abstract Background Axillary lymph node dissection (ALND) has been the standard of care for breast cancer patients with sentinel lymph node (SLN) metastasis. It is now under discussion since the publications of ACOZOG Z0011 and NSABP-32. The 1–3% rate of axillary recurrence is very low in these studies, whereas the rate of additional nodal metastasis after the completion of ALND varies from 15% to 35%. The purpose of this study was to determine the optimal number of nodes to be removed in order to obtain an axilla free of disease after initial surgery. Patients and methods: 4928 consecutive patients treated for breast cancer ≤ 2 cm with primary breast surgery with SNB between 2000 and 2009 were reviewed from the Institut Curie breast cancer prospective database. 1165 patients with a positive SLN (macrometastasis, micrometastasis and isolated tumor cells) underwent ALND. The proportion of patients with positive ALND was analysed according to the total number of sentinel lymph nodes biopsied. Results were compared with Chi-square test for qualitative variables and with Kruskal-Wallis for quantitative variables. Results: Among the 1165 patients, 308 (26.4%) had a positive ALND. Among them, 81.1% of patients had a macrometastasis in the SLN versus 45.6% in the 857 patients with negative ALND (p<0.0001); 10.8% had a micrometastasis versus 31.4% (p<0.001) and 8.1% of patients had isolated tumor cells in the SLN versus 23% (p<0.001). The proportion of patients with positive ALND decreased with the number of sentinel nodes removed (Figure 1), independently of the number of positive SLN. Among the 1165 patients, the rate of patients with 5 nodes removed or more and with residual disease in the axilla was < 1% (n=11). Those patients could have avoided completion ALND, representing 3.6% of the total positive ALND that would have been neglected. Conclusions: We showed that patients with positive SLN have a very low risk (<1%) of residual disease in the axilla when 5 nodes or more have been removed. This number which is a major component of nomograms, could be used as a threshold to avoid completion ALND. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-07-17.