Radiotherapy May Play an Important Role in Improving the Efficacy of Breast-Conserving Therapy Compared with Mastectomy in Patients with T1-2N1M0 Breast Cancer

Abstract

To evaluate if breast-conserving therapy achieved superior efficacy to modified radical mastectomy in patients with T1-2N1M0 breast cancer. 2776 women with T1-2N1M0 breast cancer treated from 1999 to 2013 were retrospectively reviewed. All had received lumpectomy or mastectomy and axillary lymph node dissection without neoadjuvant chemotherapy. The median age was 49 years. 2484 patients underwent modified radical mastectomy (MRM), 580 (23.3%) of them received postoperative RT (MRM + RT). 292 patients received breast-conserving surgery (BCT), all of them received postoperative RT. For the whole group, 92.7% of received postoperative chemotherapy and 4.9% received trastuzumab targeted therapy. Of the 2148 patients with ER and/or PR positive, 87.7% received hormonal therapy. Survival and recurrence rates were calculated by using the Kaplan-Meier method and compared by log-rank test. Multivariable analysis was estimated by using the Cox proportional hazards model. At a median follow-up of 59 months (range, 1-257 months), the 5-year overall survival (OS) of the BCT and MRM groups was 97.9% and 92.9% (p= 0.014), and the 5-year locoregional recurrence (LRR) was 2.3% vs 6.1% (p= 0.022). Of MRM group, the 5-year OS was 92.7% in MRM alone and 93.5% in MRM + RT (p = 0.037), and the 5-year LRR was 6.3% and 5.2%, respectively (p = 0.188). Furthermore, the 5-year OS of BCT group was significantly higher than that of MRM alone (p = 0.007), however there was no significant difference in OS between BCT and MRM + RT (P = 0.160). The 5-year LRR of BCT group was significantly lower than that of MRM alone (p = 0.016), but had no significant difference with MRM + RT (p = 0.094). Univariate analysis showed that age ≤ 60 years, tumor grade I-II, T1, luminal subtype, no lymph-vascular invasion, BCT, RT, chemotherapy and hormonal therapy were favorable factors of OS (P <0.05). Age > 60 years, tumor grade I-II, T1, one axillary lymph node metastasis, luminal subtype, BCT, RT and hormonal therapy were favorable factors of LRR (P <0.05). Multivariate analysis showed that age (p = 0.009), T stage (p <0.001), molecular subtype (p = 0.009) and chemotherapy (p <0.001) were independent prognostic factors for OS. RT (p = 0.054) and hormonal therapy (p = 0.063) had a trend to improve OS. Age (p = 0.034), T stage (p = 0.002), molecular subtype (p <0.001), RT (P = 0.001) and the number of positive axillary lymph node (P <0.001) were independent prognostic factors for LRR. The type of breast surgery had no significant effect on OS (p = 0.388) and LRR (p = 0.836). The type of breast surgery had no significant effect on the prognosis of patients with T1-2N1M0 breast cancer. Postoperative radiotherapy significantly reduces the risk of locoregional recurrence and might improve overall survival, suggesting that it may be required for majority of patients with mastectomy.