Intraoperative radiation therapy

Intraoperative radiation therapy is a rediscovered technique that appears from preliminary data to be valuable in the treatment of gastric, pancreatic, and colorectal carcinomas. Single radiation doses (10-20 Gy) are delivered with electron beam or orthovoltage x rays to a tumor site during an operation. This ''boost'' radiation dose is supplemented with either conventional preoperative or postoperative treatment to achieve high total doses in only the tumor, without causing damage to the surrounding normal tissues (e.g., stomach, small instentine, colon). This technique appears safe but there are limitations in some clinical situations related to large field sizes and certain normal tissues (e.g., peripheral nerve). The radiobiologic data from large animal studies and an update of the results from ongoing clinical trials are discussed