Eight-year update of a prospective study of wide excision alone for small low- or intermediate-grade ductal carcinoma in situ (DCIS).

Whether wide excision with margins ≥1 cm is sufficient treatment for small low- or intermediate-grade ductal carcinoma in situ (DCIS) is unclear. This is an updated analysis of a phase II, single-arm, prospective trial testing this hypothesis. A total of 158 patients with low- or intermediate-grade DCIS who underwent wide excision alone (without radiation or tamoxifen) were entered onto the trial from 1995 to 2002. Entry criteria included mammographic extent ≤2.5 cm, predominantly low or intermediate nuclear grade, and excision with final microscopic margins ≥1 cm. Eight-year minimum potential follow-up was required for inclusion in the analysis; the final population comprised 143 patients. Cumulative incidence curves were generated to assess rates of local recurrence (LR) or other events. Median follow-up time was 11 years. Nineteen patients (13 %) had LR as a first event within 8 years. Thirteen LR (68 %) were DCIS only and six (32 %) were invasive. Fourteen (74 %) occurred in the original quadrant. The 10-year estimated cumulative incidence of LR was 15.6 %. The estimated annual percentage rate of LR was 1.9 % per patient-year. With longer follow-up, there remains a substantial and ongoing risk of LR in patients with favorable DCIS treated with wide excision margins without radiation. This information should be useful as patients and clinicians weigh the options of wide excision with and without radiation.