[Intraoperative radiation therapy with high-energy electron beams]

Over the last two decades, intraoperative radiation therapy (IORT) has been developed using high-energy electron beams in Japan, and more recently in the United States and other countries. IORT is a potentially innovative treatment modality for radioresistant cancers of the brain, abdomen, pelvis, soft tissues and bone where local control is difficult to achieve by the conventional use of external beam irradiation. IORT may improve the therapeutic ratio of tumor control vs. normal tissue injury through the direct visualization of tumors at the time of surgical exploration which leads to precise determination of the target volume, by the physical exclusion (operative mobilization) of dose-limiting normal tissues and by the selection of appropriate electron-beam energies. In this article, the historical background, the biological and physical rationale and the clinical aspects are reviewed.