Breast-conserving surgery without axillary lymph node surgery or radiotherapy is safe for HER2-positive and triple negative breast cancer patients over 70 years of age.

The prognosis of elderly patients with hormone receptor-positive breast cancer is very good, and their survival is unaffected by performing breast-conserving surgery (BCS) without radiotherapy. Therefore, we aimed to verify that BCS without axillary lymph node dissection, sentinel lymph node biopsy, or radiotherapy (BCSNR) is safe for patients over 70 years of age with luminal-type breast cancer, as well as for those with HER2-positive and triple negative breast cancer (TNBC). This study retrospectively included 450 patients > 70-year-old with breast cancer from 2010 to 2016. The patients were divided into two groups, one treated with BCSNR and the other treated with mastectomy and axillary lymph node dissection (MALND), with a median follow-up period of 5 years. Disease-free survival (DFS), overall survival, local recurrence, distant metastasis, and ipsilateral breast tumor recurrence (IBTR) were compared between the two groups. The 5-year DFS for patients who underwent BCSNR and MALND was 90.1 and 91.3% (p = 0.903), respectively. In the BCSNR and MALND groups, respectively, the 5-year DFS for patients with luminal A type breast cancer was 99.2 and 100% (p = 0.167), that for patients with luminal B type breast cancer was 89.2 and 95.5% (p = 0.138), that for patients with HER2-positive breast cancer was 86.7 and 75.9% (p = 0.455), and that for TNBC patients was 71.7 and 89.7% (p = 0.195). IBTR significantly differed between the BCSNR and MALND groups for patients with TNBC (18.9% vs 0.0%, p = 0.040) and luminal B type patients (5.6% vs 0.0%, p = 0.043). BCSNR is not only suitable for elderly patients with luminal-type breast cancer but also for those with HER2-positive breast cancer and TNBC.