Objective  To investigate survival outcomes after breast-conserving therapy compared with mastectomy for T1-2N0M0 breast cancer patients, and to help clinical decision-making.

Methods  The clinical data of patients who met the inclusion and exclusion criteria from 2010 to 2015 were screened in the Surveillance, Epidemiology, and End Results (SEER) database and divided into breast-conserving group and mastectomy group according to the surgical method. Propensity score matching (PSM) was applied to avoid confounding factors. Univariate and multivariate Cox proportional hazard models were applied to estimate the factors associated with breast cancer-specific survival (BCSS) and overall survival (OS). The Kaplan–Meier curve analysis was performed for survival analyses, and differences were compared using the log-rank test.

Results  A total of 6,786 patients were enrolled and then 1,664 pairs of patients were finally obtained after 1:1 PSM for baseline data of the two groups. Multivariate Cox regression analysis showed that age≥70 years old[HR=2.475, 95%CI(1.672, 3.664), P<0.001], Ⅲ/Ⅳ grade Histological[HR=2.198, 95%CI(1.244, 3.883), P=0.007], breast conserving surgery[HR=0.574, 95%CI(0.397, 0.829), P=0.003] were independent factors that affect the patient’s BCSS. Breast conserving surgery could significantly improve the BCSS[HR=0.574, 95%CI(0.397, 0.829), P=0.003] and OS[HR=0.460, 95%CI(0.375, 0.564), P<0.001] of patients. Further subgroup analysis showed that breastconserving therapy significantly improved BCSS in patients with age ≤ 44 years old[HR=0.138, 95%CI(0.039, 0.485), P=0.002] and with HR+/HER2- molecular subtype[HR=0.531, 95%CI(0.333, 0.846), P=0.008].

Conclusion  For patients with T1-2N0M0 breast cancer, breast-conserving therapy is another choice, especially for those with age ≤ 44 years old with HR+/HER2- molecular subtype.

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