Radiotherapy and cellular infiltration of tumor nests.

There are several opinions which deny the therapeutic effects of preoperative irradiation. However, we have obtained favorable results in treating advanced breast and stomach cancers with preoperative irradiation using a less-fractionated irradiation method with a large dose instead of the conventional fractionated one. We adapted this kind of radiation method to improve resectability and to enhance the antigenicity of the cancer cells so as to inhibit the suppression of the immune reaction in the host. After preoperative irradiation, we examined the resected specimen histopathologically. Remarkable cellular infiltrations, such as neutrocytes, lymphocytes, macrophages and plasma cells of the tumor nests were observed; and these cellular infiltrations, after preoperative irradiation, were more remarkable than the cases without radiotherapy or with conventional fractionated radiotherapy. These cellular infiltrations suggest participation of immunoreaction and we are convinced that this kind of preoperative irradiation could enhance positive immunoreactions. The indications are that this kind of preoperative irradiation of advanced breast and stomach cancer significantly improve the cancer's resectability and curability.