Overtreatment of low-grade ductal carcinoma in situ

Importance: While the prevalence of ductal carcinoma in situ (DCIS) of the breast has increased substantially following the introduction of breast-screening methods, the clinical significance of early detection and treatment for DCIS remains unclear. Objective: To investigate the survival benefit of breast surgery for low-grade DCIS. Design, Setting, and Participants: A retrospective longitudinal cohort study using the Surveillance, Epidemiology, and End Results (SEER) database from October 9, 2014, to January 15, 2015, at the Dana-Farber/Brigham and Women’s Cancer Center. Between 1988 and 2011, 57?222 eligible cases of DCIS with known nuclear grade and surgery status were identified. Exposures: Patients were divided into surgery and nonsurgery groups. Main: Outcomes and Measures Propensity score weighting was used to balance patient backgrounds between groups. A log-rank test and multivariable Cox proportional hazards model was used to assess factors related to overall and breast cancer–specific survival. Results: Of 57?222 cases of DCIS identified in this study, 1169 cases (2.0%) were managed without surgery and 56?053 cases (98.0%) were managed with surgery. With a median follow-up of 72 months from diagnosis, there were 576 breast cancer–specific deaths (1.0%). The weighted 10-year breast cancer–specific survival was 93.4% for the nonsurgery group and 98.5% for the surgery group (log-rank test, P?