Radiosensitivity and tolerance in intraductal carcinoma of the breast

In order to elucidate the exact role of radiotherapy in breast conserving therapy, surgical specimens obtained from irradiated breast were histologically examined. The following results were obtained. 1) The therapeutic effect of irradiation on intraductal carcinomas was questionable. 2) In all of these radioresistant components, however, the expression of biological markers such as c-erbB-2, p53 or PCNA were negative. 3) The rate of ER and pS2 expression was remarkably high in three out of four residual lesions. These results demonstrate that an intraductal carcinoma of the breast has different sensitivity to irradiation. However, most of the residual lesions after radiotherapy have been less aggressive and hormone-dependent. Therefore, adjuvant endocrine therapy following breast conserving therapy may be beneficial. (author)