Radiotherapy and tamoxifen after breast-conserving surgery for DCIS.

The main controversies surrounding the management of DCIS evolve around the need for adjuvant radiotherapy (RT) after adequate local excision (LE) of localized lesions and the role of adjuvant endocrine therapy. Three recent randomized controlled trials (RCTs) have demonstrated that adjuvant RT significantly reduces the incidence of ipsilateral breast tumor recurrence (IBTR) after "adequate" LE. The role of adjuvant tamoxifen in the treatment of DCIS was evaluated in two RCTs: one demonstrated a significant reduction in IBTR with tamoxifen and the other did not. Retrospective subgroup analysis of the former demonstrated that the reduction in all breast cancer events was even greater for ER positive tumors, but no benefit was observed for ER negative lesions. The effect of tamoxifen was greater in both trials for women under 50 years.