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 months since prior interferon
* Prior somatostatin analogs or antisecretories allowed
* No other prior treatment for this cancer
* No concurrent radiotherapy to the target lesion