Comparative effectiveness study of breast-conserving surgery and mastectomy in the general population: A NCDB analysis.

Purpose: Recent studies have revealed that breast-conserving surgery (BCS) with radiotherapy (RT) led to better survival than mastectomy in some populations. We compared the efficacy of BCS+RT and mastectomy using the National Cancer Database (NCDB, USA).
Results: A total of 160,880 patients with a median follow-up of 43.4 months were included. The respective 8-year OS values were 86.5%, 72.3% and 70.4% in the BCS+RT, mastectomy alone and mastectomy+RT group, respectively (P < 0.001). After exclusion of patients with comorbidities, mastectomy (alone or with RT) remained associated with a lower OS in N0 and N1 patients. However, the OS of mastectomy+RT was equivalent to BCS+RT in N2-3 patients. Among patients aged 50 or younger, the OS benefit of BCS+RT over mastectomy alone was statistically significant (HR1.42, 95% CI 1.16-1.74), but not clinically significant (<5%) in N0 patients, whereas in N2-3 patients, the OS of BCS+RT was equivalent to mastectomy+RT (85.2% vs. 84.8%). The results of the propensity analysis were similar.
Methods: Non-metastatic breast cancers in the NCDB from 2004-2011 were identified.The Kaplan-Meier method, Coxregression and propensity score analysis were used to compare the overall survival (OS) among patients with BCS+RT, mastectomy alone and mastectomy+RT.
Conclusions: BCS+RT resulted in improved OS compared with mastectomy ± RT in N0 and N1 patients. In N2-3 patients, BCS+RT has an OS similar to mastectomy+RT when patients with comorbidities were excluded. Among patients aged 50 or younger, the OS of BCS+RT is equivalent to mastectomy ± RT.