Effect of breast conservation therapy vs mastectomy on disease-specific survival for early-stage breast cancer.

IMPORTANCE To our knowledge, there are no recent studies that directly compare survival after breast conservation therapy (BCT) vs mastectomy. OBJECTIVE To compare the breast cancer-specific survival rates of patients undergoing BCT, mastectomy alone, or mastectomy with radiation using a contemporary cohort of patients. DESIGN, SETTING, AND PARTICIPANTS We performed univariate, multivariate logistic regression, and propensity analyses to compare the hazard of death for female patients with early-stage invasive ductal carcinoma treated with BCT, mastectomy alone, or mastectomy with radiation during the period from 1998 to 2008. The data were extracted from the Surveillance, Epidemiology, and End Results database. Early-stage breast cancer was defined as having a tumor size of 4 cm or smaller with 3 or less positive lymph nodes. EXPOSURE Breast conservation therapy, mastectomy alone, or mastectomy with radiation. MAIN OUTCOMES AND MEASURES Hazard of death due to breast cancer for patients undergoing BCT, mastectomy alone, or mastectomy with radiation. RESULTS A total of 132,149 patients were included in this analysis. Breast conservation therapy was used to treat 70% of patients, mastectomy alone was used to treat 27% of patients, and mastectomy with radiation was used to treat 3% of patients. The 5-year breast cancer-specific survival rates of patients who underwent BCT, a mastectomy alone, or a mastectomy with radiation were 97%, 94%, and 90%, respectively (P < .001); the 10-year breast cancer-specific survival rates were 94%, 90%, and 83%, respectively (P < .001). Multivariate analysis showed that women undergoing BCT had a higher survival rate than those undergoing mastectomy alone (hazard ratio, 1.31; P < .001) or mastectomy with radiation (hazard ratio, 1.47; P < .001). When propensity score stratification was used, the effect of treatment method on survival was similar. CONCLUSIONS AND RELEVANCE Patients who underwent BCT have a higher breast cancer-specific survival rate compared with those treated with mastectomy alone or mastectomy with radiation for early-stage invasive ductal carcinoma. Further investigation is warranted to understand what may be contributing to this effect.