Abstract
BACKGROUND: Currently, the incidence of ductal carcinoma in situ (DCIS) is gradually increasing. Considering its overall favorable prognosis, some studies have explored exempting patients from surgery for potentially low-risk patients. This retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER) database investigates whether omitting surgery and administering only local radiotherapy (RT) affects the prognosis of patients. METHODS: A total of 2,363 patients with DCIS who did not receive surgery were identified from the SEER database. Propensity score matching (PSM) and Kaplan-Meier method were applied to analyze the impact of RT alone. Cox regression analyses and competitive risk models were used to examine factors related to the progression of DCIS to invasive cancer. RESULTS: After PSM, there were 194 patients in each of the RT and non-RT groups. Overall survival (OS) at 10 years (93.17% RT vs. 78.09% non-RT, P=0.001), breast cancer-specific survival (BCSS) at 10 years (99.45% RT vs. 90.50% non-RT, P<0.001), and invasive breast cancer progression (iBCP) at 10 years (4.23% RT vs. 13.35% non-RT, P<0.001) were statistically different between the two groups. Specific characteristics like upper outer quadrant location, certain histological types, and hormone receptor-positive status, were associated with survival benefits from RT alone. CONCLUSIONS: Based on the study of the SEER database, we found that RT alone can effectively improve patient outcomes, with a relatively low 10-year iBCP rate. Factors such as histological type, tumor size, histological grade, and hormone receptor status can influence the survival benefits and risk of RT alone for invasive breast cancer.