Purpose: The ACOSOG Z0011 trial has proven the oncological safety of sentinel lymph node biopsy (SLBx) for node negative breast cancer. Accordingly, treatment paradigm including axilla surgery was changed. We retrospectively reviewed breast cancer patients to evaluate the clinical effect of paradigm shift in breast cancer surgery after applying the Z0011 criteria. Methods: All women who underwent breast-conserving surgery at the National Cancer Center between January 1, 2000, and December 31, 2015, were enrolled and classified according to the Z0011 criteria. The primary endpoint of the study was the disease-free survival rates, and the secondary was the adverse events, especially arm lymphedema. Results: Total 361 patients were enrolled the study (271 axillary lymph node dissection [ALND] group, 90 SLBx group). After the Z0011 guideline was adopted in our institute, the use of ALND decreased, and lymph node sampling (removing only a few axillary lymph nodes) replaced ALND. The total mean number of retrieved nodes were more in ALND group (13.02) than SLBx group (3.43). However, there was no difference in the mean number of positive nodes between two groups (2.34 in ALND group vs. 1.12 in SLBx group, P=0.001). During follow-up, 25 patients experienced disease recurrence: 22 from the ALND group and three from the SLBx group. All of died seven patients were from the ALND group. The ALND group had more complications than the SLBx group (P=0.02). Arm edema occurred more frequently in the ALND group (29.5%) than in the SLBx group (5.6%), although without statistical significance (P=0.07). Conclusion In our study, we concluded that SLBx can be used safely in Z0011-eligible cohort without increased risk of locoregional recurrence. Moreover, we found that omission of ALND is favored to reduce some serious complications such as arm lymphedema.

Purpose: This study aimed to determine the incidence of male breast cancer (MBC) and its survival outcomes in Korea, and to compare these results to those for female breast cancer (FBC). Materials and Methods: We searched the Korea Central Cancer Registry and identified 227,122 breast cancer cases that were diagnosed between 1999 and 2016. Demographic and clinical characteristics and overall survival (OS) rates were estimated according to sex, age, histological type, and cancer stage. Results: The 227,122 patients included 1,094 MBC cases and 226,028 FBC cases. Based on the age-standardized rate, the male: female ratio was 0.0055:1. The most common ages at diagnosis were 60-69 years for MBC and 40-49 years for FBC (p < 0.001). Male patients were less likely than female patients to receive adjuvant radiotherapy (7.5% vs. 21.8%, p < 0.001) or adjuvant chemotherapy (40.1% vs. 55.4%, p < 0.001). The 5-year OS rates after diagnosis were 88.8% for all patients, although it was significantly lower for MBC than for FBC (76.2% vs. 88.9%, p < 0.001). In both groups, older age (≥ 60 years) was associated with shorter survival. The 5-year OS rates for the invasive histological types were 75.8% for men and 89.0% for women. The 5-year OS rates in both groups decreased with increasing cancer stage. Conclusion MBC was diagnosed at older ages than FBC, and male patients were less likely to receive radiotherapy and chemotherapy. The survival outcomes were worse for MBC than for FBC, with even poorer outcomes related to older age, the inflammatory histological types, and advanced stage. It is important that clinicians recognize the differences between FBC and MBC when treating these patients.