Higher 10-Year Survival with Breast-Conserving Therapy over Mastectomy for Women with Early-Stage (I-II) Breast Cancer: Analysis of the CDC Patterns of Care Data Base.

Background: Studies in the United States are scarce that assess the survival differences between breast-conserving surgery plus radiation (Breast-Conserving Therapy; BCT) and mastectomy groups using population-based data while accounting for sociodemographic and clinical factors that affect the survival of women with early-stage breast cancer (ESBC).

Objective: To assess whether BCT provides superior long-term overall survival (OS) and breast cancer-specific survival (BCSS) compared with mastectomy in women with ESBC, while considering key factors that impact survival.

Design: Cohort study.

Methods: We analyzed data on women aged 20 years and older diagnosed with stage I-II breast cancer (BC) in 2004 who received either BCT or mastectomy. The data were collected by 5 state cancer registries through the Centers for Disease Control and Prevention-funded Patterns of Care study. Multivariable Cox proportional hazard models, accounting for sociodemographic and clinical factors, were used to calculate hazard ratios (HRs) with 95% confidence intervals (CI). Sensitivity analysis involved optimal caliper propensity score (PS) matching to address residual confounding.

Results: Of the 3495 women, 41.5% underwent mastectomy. The 10-year OS and BCSS were 82.7% and 91.1% for BCT and 72.3% and 85.7% for mastectomy, respectively. Adjusted models showed that mastectomy recipients had a 22% higher risk of all-cause deaths (ACD) (HR = 1.22, 95% CI = [1.06, 1.41]) and a 26% higher risk of breast cancer-specific deaths (BCD) (HR = 1.26, 95% CI = [1.02, 1.55]) than BCT recipients. Sensitivity analysis demonstrated that mastectomy was associated with a higher risk of ACD (P < .05) but did not exhibit a statistically significant risk for BCD. Women with HR+/HER2+ (luminal B) or invasive ductal carcinoma BC who underwent mastectomy had higher risks of ACD and BCD compared with BCT recipients, while the hazards for ACD in triple-negative BC did not remain significant after adjusting for covariates.

Conclusion: ESBC BCT recipients demonstrate superior OS and BCSS compared with mastectomy recipients.