Breast conservation therapy versus mastectomy in patients with T1-2N1 triple-negative breast cancer: Pooled analysis of KROG 14-18 and 14-23

Purpose The aim of this study is to compare the treatment outcomes of breast conserving surgery (BCS) plus radiotherapy (RT) versus mastectomy for patients with pT1-2N1 triple-negative breast cancer (TNBC). Materials and Methods Using two multicenter retrospective studies on breast cancer, a pooled analysis was performed among 320 patients with pT1-2N1 TNBC. All patients who underwent BCS (n=212) received whole breast RT with or without regional nodal RT, while none who underwent mastectomy (n=108) received it. All patients received taxane-based adjuvant chemotherapy. The median follow-up periods were 65 months in the BCS+RT group, and 74 months in the mastectomy group. Results The median age of all patients was 48 years (range, 24 to 70 years). Mastectomy group had more patients with multiple tumors (p < 0.001), no lymphovascular invasion (p=0.001), higher number of involved lymph node (p=0.028), and higher nodal ratio ≥0.2 (p=0.037). Other characteristics were not significantly different between the two groups. The 5-year locoregional recurrence-free, disease-free, and overall survival rates of BCS+RT group versus mastectomy group were 94.6% versus 87.7%, 89.5% versus 80.4%, and 95.0% versus 87.8%, respectively, and the differences were statistically significant after adjusting for covariates (p=0.010, p=0.006, and p=0.005, respectively). Conclusion In pT1-2N1 TNBC, breast conservation therapy achieved better locoregional recurrencefree, disease-free, and overall survival rates compared with mastectomy.