[en] Objective: This course will give an overview of the role of radiation therapy in the treatment of gastrointestinal malignancies in the upper abdomen, with an emphasis on carcinomas of the stomach, pancreas and biliary tract. For each site, information will be presented related to failure patterns with conventional surgical treatment and the indications for surgery for different stages of disease. The possible uses of radiation therapy as an adjuvant to surgical resection will be discussed as well as the use of radiation therapy alone. In addition, the combination of radiation therapy with chemotherapy will be discussed for each of these sites, as well as the information available at present as to the optimal way to combine chemotherapy with radiation therapy. Radiation therapy is not generally accepted to have a role in the treatment of patients with adenocarcinomas of the stomach. This is related to the fact that gastric cancer has been standardly treated with surgical resection alone, and delivery of high dose radiation therapy to the upper abdomen can be difficult because of the sensitivity of nearby normal tissues. Nonetheless, data on failure patterns suggest that local recurrence is common in patients with disease through the gastric wall and with positive nodes. Although there is some suggestive data to indicate that radiation therapy is effective as an adjuvant, results of an ongoing trial will be necessary for determination of the exact role of radiation therapy. Possible uses of radiation therapy as preoperative therapy or given alone will also be briefly discussed. Radiation therapy has been often used in the treatment of pancreatic adenocarcinomas, either alone or combined with surgical resection. Its use is more common for this site both because of the extremely poor prognosis of standard therapies, and because of the difficulty in performing an adequate surgical resection. Data will be reviewed suggesting that radiation therapy has a role when combined with chemotherapy in patients with unresectable disease, and that radiation therapy and chemotherapy is of value as an adjuvant therapy in patients who have had a potentially curative surgical resection. There is relatively little information on the treatment of cancers of the biliary tract with radiation therapy. However, the existing data on recurrence patterns and therapy will be reviewed. The use of brachytherapy for patients with biliary obstruction will be discussed. In most tumors of the GI tract, the combination of radiation therapy with 5-FU chemotherapy seems to be more effective than radiation therapy alone. Newer information suggests that modulators of 5-FU effect such as leucovorin, or altered modes of administration such as continuous infusion, may be beneficial. These issues will be discussed as they relate to the upper abdominal malignancies