Radiation therapy for intraductal carcinoma. Is it an equal alternative? Of 213 consecutive patients with intraductal carcinoma, 109 were selectively treated with mastectomy and 104 with radiation therapy. There were eight local recurrences, seven in patients treated with radiation therapy and one in a patient treated with mastectomy. Histologically, there were 110 comedocarcinomas and 103 noncomedocarcinomas. Seven local recurrences occurred in patients with comedocarcinomas and one in a patient with a noncomedo tumor. Three (38%) of eight local recurrences (all comedo) were invasive. The 5-year actuarial survival for all subgroups was 100%. The median follow-up was 51 months. Intraductal carcinoma is unlikely to metastasize to axillary lymph nodes, and routine dissection is unnecessary. Ductal carcinoma in situ of the comedo variety is more aggressive and more likely to recur than its noncomedo counterpart. We currently view conservative therapy for patients with intraductal comedocarcinoma with caution. 