Breast conserving surgery combined with radiation therapy offers improved survival over mastectomy in early-stage breast cancer.

INTRODUCTION:Landmark trials established equivalent survival regardless of extent of breast surgery in early-stage breast cancer. However, recent studies suggest a survival advantage for breast conserving surgery (BCS) with radiotherapy (BCT). This study assesses the impact of type of surgery on overall survival (OS), breast cancer specific survival (BCSS) and local recurrence (LR) in a modern population-based cohort. METHODS:Female patients aged ≥18, pT1-2pN0, who had surgery between 2006 and 2016 were identified from Breast Cancer Outcome Unit prospective database. Neoadjuvant chemotherapy patients were excluded. Multivariable Cox regression was used to assess the effect of surgical procedure on OS, BCSS, and LR on cohort with complete data. RESULTS:BCT was performed in 8422 patients and TM in 4034 patients. The baseline characteristics differed between the groups. Mean follow up was 8.3 years. BCT was associated with increased OS HR 1.37, p < 0.001, BCSS survival HR 1.49, p < 0.001, and similar LR HR 1.00, p > 0.90. CONCLUSION:This study supports that in early-stage breast cancer, BCT has improved BCSS compared to TM without an increased risk of LR.