[Multiple primary malignant cancer and radiation induced cancer--a point of view of radiation oncology].

The cases of multiple primary malignant neoplasm and radiation induced cancer were discussed based on the experiences of Tokyo Women's Medical College in which radiotherapy has been mainly used for cancer. These cases have been increasing in number and it seems to be that the problems of them shall be gradually developed in future, because survival time of cancer patients become longer due to improvement of cancer treatment. But if the mechanisms of cancer etiology on which radiation and other many things influence, would not be clear, radiotherapy have been still principal post in cancer treatment. Systemic multidisciplinary treatment of cancer must be considered and we are looking forward to establishing it.