e12615 Background: The prognosis and management of patients with ductal carcinoma in situ (DCIS) with microinvasion (DCISM) remain controversial. Methods: We analyzed the outcomes of patients with DCIS or DCISM from the Surveillance, Epidemiology, and End Results (SEER) and the Chinese Society of Clinical Oncology (CSCO) database. Results: Microinvasion was associated with comedo type, human epidermal growth factor receptor-2 (HER2) overexpression, and estrogen receptor (ER) or progesterone receptor (PR) negative status (all P < 0.005). Despite these differences, no statistically significant disparities were observed in prognosis. SEER data showed that breast-conserving surgery (BCS) with radiotherapy was related with improved breast cancer-specific survival (BCSS) (hazard ratio HR = 0.06, P = 0.0147) in DCISM patients, as well as overall survival (OS) in both DCIS (HR = 0.42, P = 0.0025) and DCISM patients (HR = 0.26, P = 0.0002). CSCO data indicated BCS with radiotherapy tends to improve disease-free survival (DFS) compared with mastectomy (HR = 0.06, P = 0.053). Chemotherapy was associated with worsened DFS in DCIS (HR = 1.91, P = 0.007), while endocrine therapy improved DFS in hormone receptor (HR)–positive DCIS (HR = 0.46, P = 0.013) in the CSCO database. Conclusions: Although DCISM presents with more aggressive pathology, its survival outcomes are comparable to DCIS. In this study, BCS with radiotherapy was associated with more favorable survival outcomes than mastectomy, regardless of the presence of microinvasion. Chemotherapy was associated with poorer disease-free survival in DCISM.
Chen et al. (Thu,) studied this question.