Intra-operative radiation therapy in tumors of the digestive tract

All the retrospective and prospective studies concerning IORT in tumors of the digestive tract tend to substantiate a significant improvement in local control without a significant increase in survival. Improvements in the results of IORT can be expected in the near future, and may occur on several fronts: - Technological improvements: advances in the development of IORT machines, with the construction of electron accelerators specifically designed for IORT; greater precision in the systems of collimation (asymmetric collimator, multiple leaves, computerization of the control of collimation); and increased adaptability of the localizers to each clinical situation and to each patients. - Increase in the biological effects of IORT: determination of the exact role of IORT in relation to other therapeutic methods, its integration into the global therapeutic strategy for cancer, and the optimization of IORT doses should all be studied in phase II and III trials. Interesting results are expected from the combination of different methods of preoperative, intraoperative, and postoperative radiotherapy with chemotherapy; the cumulative effect of radiosensitization and cytotoxicity can bring about both local control and treatment of the general disease. In addition, the combination of hypoxic cell radiosensitizers and IORT, a source of important cellular hypoxia as a result of single doses, appears promising. - Lastly, randomized studies in a larger number of patients with objectives and methodologies to be perfected will document the actual contribution of IORT to an increase in survival as part of an overall treatment strategy for digestive tumors. At present, the prognosis remains significantly related to systemic metastatic evolution; this can only be influenced by chemotherapy, whose efficacy remains to be demonstrated. As means for better control of systemic disease are discovered, the clear benefits of local control via IORT will assume increased importance.