Randomized clinical trials (RCT) have demonstrated equivalent survival for breast-conserving therapy with radiation (BCT) and mastectomy for early-stage breast cancer. Early stage breast cancer patients who underwent BCT or mastectomy was studied to observe whether outcomes of RCT were achieved in a single institution series, and whether survival differed by surgery type when stratified by breast cancer subtypes.
Information was obtained from the institutional breast cancer data base with stage I or II breast cancer between 1990 and 2010, who were treated with either BCT or mastectomy and followed for vital status through December 2014. Cox proportional hazards modeling was used to compare overall survival (OS) and disease-specific survival (DSS) between BCT and mastectomy groups. Analyses were stratified by breast cancer subtype.
A total of 3486 women fulfilled eligibility criteria. Women undergoing BCT had improved OS and DSS compared with women with mastectomy (adjusted hazard ratio for OS = 0.69, 95% CI = 0.51-0.95, p = 0.0.023; adjusted hazard ratio for DSS =0.68, 95%CI =0.48 -0.96, p = 0.029). 10 year overall survival rate in women undergoing BCT was 95.2% in Luminal A, 94.8% in Luminal B, 84.8% in Luminal/HER2, 91.5% in HER2 enriched and 92.1% in Triple negative. 10 year overall survival rate in women with mastectomy was 91.2% in Luminal A, 82.3% in Luminal B, 89.5% in Luminal/HER2, 86.2% in HER2 enriched and 88.4% in Triple negative.The group achieving greatest benefit in OS and DSS with BCT relative to mastectomy were stage II luminal B patients (adjusted hazard ratio for OS = 0.28, 95% CI = 0.1-0.82, p = 0.02; adjusted hazard ratio for DSS =0.31, 95%CI =0.11 -0.91, p = 0.0329).
Among patients with early stage breast cancer, BCT was associated with improved DSS and OS. These data provide confidence that BCT remains an effective alternative to mastectomy for early stage disease. The group achieving greatest benefit in DSS and OS with BCT relative to mastectomy were stage II Luminal B patients.
Clinical trial identification
Legal entity responsible for the study
Koo Foundation Sun Yat-sen Cancer Center, Taipei, Taiwan.
Has not received any funding.
All authors have declared no conflicts of interest.