Not everyone with ductal carcinoma in situ of the breast treated with breast preservation needs post-excisional radiation therapy

While the results of NSABP protocol B-17 and EORTC protocol 10853 prove that radiation therapy decreases the overall rate of local recurrence in patients with DCIS, there are clearly subgroups of patients who do not benefit from radiation therapy or whose benefit is so small that the addition of radiation therapy to their treatment regimen is simply not worthwhile. Identifying these subgroups is of paramount importance. Factors like tumour size, margin width, nuclear grade, and the presence or absence of comedonecrosis can be used to define favorable subgroups that do not require post-excisional radiation therapy. The most recent results of NSABP protocol B-17 and EORTC protocol 10853 confirm that, regardless of treatment, there is no difference in the single most important end-point: survival. If there is no difference in breast cancer mortality, it is clearly worthwhile to try to define the subgroups of patients who can be spared the time, costs, and side-effects of a treatment that they do not need.