Breast-conserving surgery versus mastectomy for older women with triple-negative breast cancer: population-based study.

To assess whether the poor prognosis of triple-negative breast cancer (TNBC) necessitates a more aggressive surgical approach. We examined the association of: breast-conserving surgery (BCS); BCS plus radiotherapy; mastectomy; and mastectomy plus radiotherapy with overall and breast cancer-specific survival of stage I-III TNBC patients aged 66 years and older. We used unweighted and inverse probability of treatment weighted Cox proportional hazards regression and the Fine and Gray sub-distribution model. Among 4333 women, individuals who were selected for BCS, mastectomy or mastectomy plus radiotherapy had lower adjusted overall and breast cancer-specific survival compared with women who had BCS plus radiotherapy. In this population-based study, women with TNBC treated with BCS plus radiotherapy have a better prognosis than those treated with BCS, mastectomy or mastectomy plus radiotherapy. Given the poor prognosis of TNBC and selection bias inherent in observational studies, these findings should be confirmed in further studies such as randomized clinical trials.