Comparison of Prognosis Between Breast Conserving Therapy and Mastectomy in Early Breast Cancer: A Propensity Score Matching Analysis

Abstract

The survival benefit of breast conserving therapy (BCT) over mastectomy has been shown in recent studies. The aim of the present study is to further explore oncologic outcomes between BCT and mastectomy in modern era.Continuous patients diagnosed with stage pT1-2, pN0-1, M0 breast cancer between 2009 and 2015 in one hospital were retrospectively reviewed. Recurrence patterns were evaluated among whole breast irradiation (WBI), mastectomy-alone, WBI with RNI and PMRT. Two separate comparisons of survival outcomes were performed using 1:1 propensity score matching (PSM): WBI versus mastectomy-alone, WBI with RNI versus PMRT (including RNI).2429 patients were enrolled in this analysis. The median follow up was 72 months (range, 54 to 94 months). Compared with those treated with mastectomy, patients who received BCT were younger (P<0.001) and with smaller tumors (P = 0.000). In addition, patients with BCT were more likely to receive RNI (OR, 2.579; P = 0.001). Nonetheless, there were no differences in chemotherapy regimens between patients who received BCT and those who underwent mastectomy (OR, 1.396; P = 0.062). For first recurrence, WBI patients demonstrated the lowest rate of distant metastases (3.1%), followed by mastectomy (4.1%), WBI with RNI (7.6%), PMRT (8.3%) (P = 0.007). Besides, WBI had the lowest rate of lung, liver and brain metastases (P = 0.047). There were no significant differences in terms of locoregional recurrence (P = 0.155) or contralateral breast cancer (P = 0.807) as first recurrence. After PSM, 904 patients (452 in the WBI group and 452 in the mastectomy-alone group) and 188 patients (94 in the WBI with RNI group and 94 in the PMRT group) were included for further analysis, respectively. There was no difference between WBI group and mastectomy-alone group in terms of overall survival (OS), breast cancer specific survival (BCSS), disease free survival (DFS), distant metastasis free survival (DMFS) and regional recurrence free survival (RRFS). No significant difference of local recurrence free survival (LRFS) was found between WBI and mastectomy. In subgroup analysis, patients with grade I/II tumor had a superior DMFS over mastectomy alone (P = 0.005). The 10-year RRFS was significantly higher in patients who underwent WBI with RNI versus PMRT (100% vs 90.3%, P = 0.025). In patients≥40 years and with grade I/II tumor (n = 76), WBI with RNI group had better DFS (P = 0.035) and DMFS (P = 0.035) over PMRT.In the whole cohort, there exist differences in recurrence patterns, while no differences in overall survival between WBI and mastectomy-alone group or WBI with RNI and PMRT group. However, WBI patients did show superior DMFS in patients with grade I/II tumor over mastectomy alone. WBI with RNI group had a higher RRFS rates compared with PMRT. Patients ≥ 40 years and with grade I/II tumor had better DFS and DMFS following WBI with RNI compared with PMRT. BCT is recommended to be therapeutic choice of priority in early breast cancer.