Combination Chemotherapy as First-Line Therapy in Treating Patients With Locally Advanced or Metastatic Neuroendocrine Tumors of the Duodenum or Pancreas That Cannot Be Removed By Surgery

DISEASE CHARACTERISTICS: * Diagnosis of neuroendocrine tumor of the duodenum/pancreas by histology or bone scan * Functional or nonfunctional tumor * Tumor meets ≥ 1 of the following criteria: * Hepatic or extrahepatic metastases * Progressive locally advanced tumor (primary or adenopathies) * Unresectable disease * Tumor differentiated and meets the following criteria: * Ki 67 ≤ 15% * Less than 10 mitoses per 10 large fields * Measurable or evaluable disease * Target lesions must meet 1 of the following criteria within the past 6 months: * Increase of 20% in the longest diameter * New metastases detected * Minimum size of lesions must be 1 of the following: * More than 15 mm for metastases * More than 50 mm for primary tumor or local lymph nodes PATIENT CHARACTERISTICS: * WHO performance status 0-2 * Creatinine ≤ 1.5 mg/dL * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Bilirubin ≤ 1.8 mg/dL * No coronary insufficiency or symptomatic cardiac disease * No intestinal obstruction, enteropathy, or uncontrolled chronic diarrhea * No Gilbert's disease * No psychological, social, familial, or geographic condition that would preclude study treatment * Not pregnant or nursing * Fertile patients must use effective contraception during and for 6 months after completion of study therapy * No other condition that would preclude study therapy PRIOR CONCURRENT THERAPY: * No prior adjuvant radiotherapy * At least 3 mo…