Local and systemic outcomes in DCIS based on tumor and patient characteristics: the radiation oncologist's perspective.

Four randomized clinical trials have shown unanimously the benefit of 50 Gy whole-breast radiotherapy in breast-conserving therapy (BCT) for ductal carcinoma in situ (DCIS). The risk of both DCIS and invasive local recurrence is reduced with about 50%, and this effect is similar for all clinical and histological subgroups analyzed. Younger age and involved margin status are the most important factors for an increased risk of local recurrence. In these subgroups, even with radiotherapy, the observed local recurrence rates are more than 20% at 10 years, which is considerably higher than reported local recurrence rates after BCT for invasive breast cancer. The optimal radiotherapy dose in BCT for DCIS has yet to be established. Also, at present, a subgroup of lesions in which the recurrence rate is so low that radiotherapy can be safely omitted has not yet been identified.