Abstract P2-14-22: Evaluation of male breast cancer and the application of sentinel lymph node biopsy: A multi-center retrospective study

Abstract Objective:Sentinel lymph node biopsy (SLNB) is currently used as a routine treatment for breast cancer patients. Many clinical studies, such as the NSABP B-32, have demonstrated that SLNB can safely replace axillary lymph node dissection (ALND) for patients with clinically node-negative breast cancer. However, it may not be applicable for male breast cancer (MBC) patients because they have notably different clinicopathological features from those occurring in females. There is a lack of evidence of SLNB application and safe exemption from ALND in MBC patients. This study aimed to evaluate the application of SLNB to provide information for the standardized treatment of MBC patients. Methods:The MBC patient records from four institutions ranging from January 2001 to November 2020 were retrospectively reviewed. Patients undergoing surgery as a primary treatment were included. Patients with stage IV and non-primary breast cancer were excluded. Patients were followed up postoperatively for survival analysis. The primary outcome was disease-free survival (DFS), and the secondary outcome was overall survival (OS). Results:There were 220 MBC patients with a median age of 60 (range 24-88) years and an average tumor size of 2.3 cm (range 0.5 cm - 6.5 cm). MBC patients were characterized by old age, advanced stage, and higher pathological grade. The median follow-up time was 5.0 (range, 1.0-17.3) years. Survival analysis showed the 5-year DFS and OS were 73.5% and 83.3%, respectively. 66 patients (30%) underwent SLNB and 39% of them showed positive results. 157 patients (71%) underwent ALND, while only half of them had positive nodes, causing unnecessary complications. For 92 patients at clinical early-stage (stage I or IIA), 28 patients only had SLNB as axillary treatment, 26 patients only had ALND and 38 patients underwent SLNB and ALND. From Kaplan-Meier survival analysis, we found that the SLNB showed a non-inferiority to the ALND treatment in DFS (p=0.18) and OS (p=0.055). Conclusion:MBC patients are older at the time of diagnosis and present a higher pathological grade. There are certain obstacles to the broad application of SLNB due to the lower proportion of clinically-negative lymph node patients. However, it is undeniable that SLNB can safely and effectively exempt MBC patients at early-stage with clinically-negative nodes from ALND to reduce subsequent complications. It’s still an ideal criterion for the axillary staging of MBC patients. Clinicopathologic characteristics of MBC patients Citation Format: Qingyao Shang, Ya Wei, Guangdong Qiao, Jingruo Li, Xin Wang. Evaluation of male breast cancer and the application of sentinel lymph node biopsy: A multi-center retrospective study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-22.