Long-term outcomes of breast-conserving therapy for women with ductal carcinoma in situ.

Improved imaging, surgical techniques, and pathologic evaluation likely have decreased local recurrence rates for patients with ductal carcinoma in situ (DCIS). We present long-term outcomes of a large single-institution series after breast-conserving surgery (BCS) and adjuvant radiation therapy (RT). We retrospectively reviewed the records of 245 women treated for DCIS with BCS and RT between 2001 and 2007. Competing risk analysis was used to calculate local recurrence (LR) as a first event with the development of a second non-breast malignancy, contralateral breast cancer, and death as competing first events. At a median follow-up of 10.6 years, 4 patients had a LR (2 DCIS, 2 invasive) as a first event with a cumulative LR incidence of 0.0% and 1.5% at 5 and 10 years, respectively. Most patients had > 2 mm margins (90%), specimen radiographs (93%), and received a tumor bed boost (99%). The majority (60%) of patients with hormone receptor-positive disease received adjuvant endocrine therapy. Ten-year cumulative incidence of contralateral breast cancer (CBC) was 7.9%, second non-breast malignancy was 4.5%, and death unrelated to breast cancer was 3.5%. Family history, age at diagnosis, and receipt of endocrine therapy were not significantly associated with the development of CBC (all P > 0.05). With mature follow-up, our rates of local recurrence following breast-conserving therapy for DCIS remain very low (1.5% at 10 years). The incidence of CBC was higher than the LR incidence. Predisposing factors for the development of CBC are worthy of investigation.