LAUSR

Purpose: To identify whether a certain group of breast ductal carcinoma‐in‐situ (DCIS) patients can be treated with breast‐conserving surgery (BCS) alone; to analyze the clinicopathologic features of DCIS and tamoxifen administration in patients treated with BCS who developed ipsilateral breast tumor recurrence (IBTR). Patients and Methods: Data for 375 women with breast DCIS who underwent BCS at our institute between June 2003 and October 2010 were analyzed. The patients were divided into different categories according to the recurrence risk predicted using the California/Van Nuys Prognostic Index (USC/VNPI) score (4‐6, 7‐9, and 10‐12), Eastern Cooperative Oncology Group (ECOG) E5194 criteria, or combined risk features with USC/VNPI score and ECOG E5194 criteria. The IBTR and disease‐free survival (DFS) rates were calculated by the Kaplan‐Meier method. The prognostic effects of age, tumor size, tumor grade, margin width, estrogen receptor status, USC/VNPI score, low‐risk characteristics, and tamoxifen use were evaluated by log‐rank tests. Results: Of the patients, 168 were treated with breast irradiation after BCS and 207 were not. The patients who were treated with radiotherapy (RT) tended to be younger (< 40 years), to have higher USC/VNPI scores (7‐9), and to meet the ECOG E5194 non–cohort 1 criteria. The 7‐year risk of IBTR was 6.2% (n = 11) in the patients who received irradiation and 9.0% (n = 22) in those who did not. DFS rates were better in the patients who underwent RT than in those who did not (93.3% vs. 88.5%, P = .056). Among the patients who underwent BCS alone, age ≥ 40 years, margin width > 10 mm, USC/VNPI scores 4‐6, ECOG E5194 cohort 1 criteria, estrogen receptor–positive status, and tamoxifen use predicted lower IBTR and better DFS rates. In the multivariate analysis, combined low‐risk characteristics (USC/VNPI scores 4‐6 and meeting the ECOG E5194 cohort 1 criteria) were identified as an independent prognostic factor of lower IBTR (P = .028) and better DFS (P = .005). Conclusion: RT reduces the risk of IBTR after BCS for DCIS of the breast. Patients with combined low‐risk characteristics (USC/VNPI scores 4‐6 and meeting the ECOG E5194 cohort 1 criteria) may be adequately treated with BCS alone.