Outcomes of screening-detected ductal carcinoma in situ treated with wide excision alone.

BACKGROUND: Ductal carcinoma in situ (DCIS) is commonly identified on screening mammography. Standard treatment for localized DCIS is wide local excision (WLE) and adjuvant radiotherapy. This approach represents overtreatment in many cases, where the DCIS would never have become clinically significant, or where less intensive treatment would have been satisfactory. We reviewed the medium-term outcome of a cohort of screen detected DCIS patients treated mainly with WLE without radiotherapy.
METHODS: All patients diagnosed with DCIS at NorthWestern BreastScreen between January 1994 and December 2005 were identified from a prospective database. Demographic, pathological, treatment, and outcome data were collected and analyzed. Survival and local recurrence (LR) rates were determined, and associations between various factors and recurrence were analyzed.
RESULTS: A total of 422 patients were diagnosed with DCIS. There were 400 patients treated with WLE, and 27 of these received adjuvant radiotherapy. The 5- and 8-year overall and breast cancer specific survival rates were 96.1 and 91.3%, and 99.6 and 99.3%, respectively. The local recurrence rate was 15.4 and 17.1% at 5 and 8 years. Of 56 local recurrences, 34 had WLE after recurrence, 16 of which had adjuvant radiotherapy. No single factor was statistically significantly associated with local recurrence, although combining factors revealed groups where the LR rate was less than 5%.
CONCLUSIONS: Breast cancer specific mortality was very low in this cohort of older patients with screen-detected DCIS. There was a moderate rate of local recurrence that could usually be salvaged with breast conservation. Decisions regarding adjuvant radiotherapy should take these findings into account.