A Phase I Trial of Gemcitabine and Radiation in Locally Advanced Unresectable Cancer of the Pancreas

DISEASE CHARACTERISTICS: Histologically or cytologically proven unresectable adenocarcinoma of the pancreas or ampulla of Vater. Surgical consult at NCI confirming unresectability fulfills requirement. Unresectable disease defined as tumor with: Gross involvement of regional nodes or direct extension to any of the following sites: Duodenum, Spleen, Bile duct , Colon, Peripancreatic tissue, Adjacent large vessels, Stomach. Metastatic disease requiring local radiotherapy allowed. No CNS metastasis. No lymphomas or neuroendocrine tumors. No peritoneal carcinomatosis. PRIOR/CONCURRENT THERAPY: Biologic Therapy: More than 4 weeks since immunotherapy. Chemotherapy: No prior chemotherapy for newly diagnosed disease. More than 4 weeks since chemotherapy for recurrent disease (6 weeks since nitrosoureas, mitomycin, or suramin). Endocrine Therapy: More than 4 weeks since hormonal therapy. Radiotherapy: No prior radiotherapy for newly diagnosed disease. No prior abdominal or pelvic radiotherapy. More than 4 weeks since radiotherapy for recurrent disease. No prior radiotherapy for locally advanced disease after resection allowed. Surgery: Prior resection allowed. Biliary decompression or gastric bypass allowed. PATIENT CHARACTERISTICS: Age: 18 and over. Performance status: ECOG 0-2. Hematopoietic: ANC greater than 2,000/mm(3). Platelets greater than 100,000/mm(3). Hepatic: AST/ALT no greater than 2.5 times normal. Renal: Creatinine less than 1.5 mg/dL. Creatinine clearance at least 60 mL/min, Cardiovascular: No myocardial infarction within 6 months. No unstable angina. No congestive heart failure (NYHA class III/IV). OTHER: HIV seronegative. No medical or psychiatric contraindication to protocol therapy. No concurrent malignancy other than: Skin cancer, Cervical carcinoma in situ. No pregnant or nursing women. Adequate contraception required of fertile patients.