DISEASE CHARACTERISTICS: Histologically or cytologically confirmed adenocarcinoma of the pancreas Ductal adenocarcinoma Mucinous noncystic carcinoma Signet ring cell carcinoma Adenosquamous carcinoma Undifferentiated (anaplastic) carcinoma Mixed ductal endocrine carcinoma Well differentiated adenocarcinoma Moderately well or poorly differentiated adenocarcinoma Undifferentiated ductal carcinoma No papillary cystic carcinomas, sarcomas, or tumors arising from the endocrine pancreas Pathological confirmation of a metastatic site allowed Clinical documentation of pancreatic involvement and no evidence of another primary allowed Locally advanced or distant metastatic disease surgically incurable No known brain metastases

PATIENT CHARACTERISTICS: Age: Not specified Performance status: Zubrod 0-1 Life expectancy: Not specified Hematopoietic: Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) SGOT or SGPT no greater than 2.5 times ULN Renal: Creatinine no greater than 2.0 mg/dL Other: Ability to swallow and/or receive enteral medications via gastrostomy feeding tube No intractable nausea or vomiting No other prior malignancy within the past 5 years except adequately treated basal or squamous cell skin cancer, carcinoma in situ of the cervix, or stage I or II cancer in remission Not pregnant or nursing Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior or concurrent immunotherapy Chemotherapy: No prior chemotherapy No prior adjuvant or neoadjuvant chemoradiotherapy, including for advanced pancreatic cancer No other concurrent chemotherapy Endocrine therapy: No prior or concurrent hormonal therapy Radiotherapy: See Chemotherapy No prior radiotherapy, except for palliation to metastatic sites No concurrent radiotherapy Surgery: See Disease Characteristics At least 2 weeks since prior surgery for pancreatic cancer and recovered Prior partial resections of the stomach and duodenum for pancreatic cancer allowed No prior major resection of the small intestine Prior pancreaticduodenectomy for pancreatic cancer allowed Other: No concurrent proton pump inhibitors (e.g., omeprazole) Concurrent antacids or H2 blockers allowed No other concurrent therapy for pancreatic cancer