Abstract P4-10-14: Risk of Ipsilateral Breast Events in Patients with Ductal Carcinoma In Situ after Local Excision

Abstract

Abstract Purpose To determine the risk of ipsilateral breast events (IBE) in patients with ductal carcinoma in situ (DCIS) treated with local excision. Patients and Methods We retrospectively identified 692 patients who had undergone local excision from 1968 through 2007 at our institution with a final diagnosis of DCIS. Factors evaluated included age, race, method of detection, menopausal status, bloody nipple discharge, histological type, final margin status, grade, status at last follow-up and recurrence information. An IBE was defined as the development of breast cancer of invasive histology or DCIS (but not lobular carcinoma in situ) in the treated breast. Results At a median follow-up of 6.1 years, 47 (6.8%) IBEs occurred in the 692 patients. Among 47 IBE, 23 (48.9%) were DCIS and 19 (40%) were invasive cancer and 5 (10.6%) were unknown type of IBE. Patients with IBE were younger (53 Vs 57, P=0.04). Whether patients had final positive margin (4 patients) had no influence on IBE. Use of a Cox proportional hazards model showed that patients with high grade tumors and those who did not receive adjuvant radiation therapy (XRT) were more likely to have an IBE (Hazard ratio: 4.1, 95% CI:1.3-13.4, P=0.019). The 5-year rate of ipsilateral breast events for patients with grade III DCIS who did not undergo adjuvant radiation therapy was significantly higher than all others: 15% vs. 4.6% compared to grade I/II with XRT, 15% vs. 10% compared to grade I/II without XRT, and 15% vs. 9.9% in grade III with XRT (P=0.017). Conclusions Patients with low or intermediate grade DCIS have an acceptably low rate of ipsilateral breast events after local excision with adjuvant radiation therapy. Patients with high-grade lesions treated without irradiation have a rate of IBE of 15% at 6 years, suggesting that excision alone is inadequate treatment in this group. Further follow-up is necessary to document long-term results. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-10-14.