An organized multi-institutional interdisciplinary evaluation of role of radiation therapy alone or combined with chemotherapy in treatment of adenocarcinoma of the gastrointestinal tract.

Adenocarcinomas of the gastrointestinal tract have generally been considered to be radioresistant. In 1974-1975, following an early lead from the Mayo Clinic (Rochester, MN), the Gastrointestinal Tumor Study Group initiated a series of clinical trials of radiation therapy and chemotherapy as surgical adjuvant programs for patients with pancreatic and rectal cancer and for the treatment of locally unresectable gastric and pancreatic adenocarcinomas. The first protocols for pancreatic cancer included a controlled trial of radiation therapy and chemotherapy following pancreatoduodenectomy or total pancreatectomy and also a randomized trial of high-dose radiation therapy, with or without chemotherapy, compared to a lower dose of radiation therapy combined with chemotherapy for patients with locally unresectable tumors. In the treatment of locally incurable gastric cancer, radiation therapy plus chemotherapy was compared to chemotherapy alone, while the rectal trial was a randomized comparison of radiation therapy; chemotherapy; the combination of radiation therapy and chemotherapy; and no further treatment following surgical extirpation. In all cases, the agent used during the course of radiation was 5-fluorouracil. Subsequent trials in pancreatic cancer compared radiation combined with either 5-fluorouracil or doxorubicin and included a pilot study of hyperfractionated radiation therapy combined with 5-fluorouracil. Confirmatory trials were undertaken and are still under analysis in gastric cancer and in rectal cancer. A follow-up trial in pancreatic cancer was developed to establish the importance of the radiation therapy component of combined modality therapy in the treatment of patients with locally unresectable disease. A final study examined the potential for radiation therapy of the liver and systemic chemotherapy in the prevention of metastatic adenocarcinoma of the colon.(ABSTRACT TRUNCATED AT 250 WORDS)