After radiation therapy for breast cancer, the risk of sarcoma, lung cancer, and other breast cancers have been described in the medical literature. From France, we have reports on thousands of women treated with radiation therapy for breast cancer over the last few decades.enerally, the risk of developing a radiation induced malignancy after treatment of cancer is very small, though certainly a scary thought. Remarkably though, radiotherapy related cancers account for a small minority of second cancers which develop in patients after treatment for a first cancer.