History, preliminary results, complications, and future prospects of intraoperative radiotherapy.

Intraoperative electron beam radiotherapy (IORT) is a new combined modality therapy in the treatment of cancer. IORT is delivered during a surgical procedure to a tumor or tumor bed and areas of possible local regional spread, with the ability to shield or physically move normal tissues and organs out of the treatment volume. IORT is feasible for various intraabdominal, retroperitoneal, pelvic, and other malignancies. It is possible to increase the total radiation dose, thereby improving the therapeutic ratio; a better local control without an increasing morbidity. Although the optimum use of IORT is still unknown, it is believed that its greatest value is in combination with maximal surgical resection of the tumor with or without external beam radiotherapy (EBRT). IORT is still an experimental treatment modality combining surgery, EBRT, and if necessary, chemotherapy. Because IORT is an expensive treatment method, it is important to determine which method is the best and most convenient for the patient. The answer can be given only when prospective, randomized clinical IORT trials and cost-effectiveness studies are initiated.