Prognosis of breast-conserving surgery versus total mastectomy in young breast cancer patients based on SEER and Hebei Province cohort

Objective: To investigate the impact of breast-conserving surgery (BCS) and total mastectomy (TM) on the prognosis of young non-metastatic breast cancer patients. Methods: Surveillance, Epidemiology and End Results (SEER) database was collected for cases from 2010-2015, and patients’ data from 2015-2018 were likewise collected from the Hebei Provincial Tumor Registry. The Chi-square test and Fisher's exact probability method were used to compare differences in clinicopathological characteristics between treatment groups. Using univariate, multivariate Cox regression and propensity score matching (PSM) to analyze the prognosis of patients undergoing different procedures. Results: A total of 9106 cases were collected from SEER database with a median follow-up time of 75 months. Race, Grade, T-stage, N-stage, histological type, ER status and HER2 status were independent prognostic factors for patients in the BCS group; race, T-stage, N-stage, PR status and HER2 status were independent prognostic factors for patients in the TM group. There was no significant difference in Overall survival (5-year OS rate: 93.2% vs. 93.4%) and Breast cancer-specific survival (5-year BCSS rate: 93.7% vs. 93.9%) between patients in the BCS and TM groups, regardless of before and after PSM (P>0.05). Compared to patients in the BCS group who had better OS than the TM group in 701 cases in Hebei Province (5-year OS rate: 97.0% vs 91.9%, P<0.05). Among patients who received radiotherapy, BCS patients had better OS than TM patients, and among patients with grade I as well as radiotherapy, BCS patients had better BCSS. Conclusions: The prognosis of patients undergoing BCS is similar to that of patients undergoing TM. As younger patients increasingly undergo BCS, more attention should be paid to the prognosis of this group.