In two recent randomized clinical trials from Denmark and Canada the usefulness of radiotherapy was evaluated in premenopausal patients with breast cancer who had been operated and in whom the findings indicated a poor prognosis. Over 2000 patients participated. After follow-up periods of 10 and 15 years, respectively, addition of locoregional therapy to mastectomy and chemotherapy with cyclophosphamide, methotrexate and fluorouracil (CMF) was found to result in better locoregional control and a better disease-free survival. These studies also demonstrated, for the first time, that the overall survival was increased after postoperative radiotherapy. In view of these findings, the indication for postoperative locoregional radiotherapy in breast cancer in the Netherlands should be reconsidered.