ZD 1839 Plus Combination Chemotherapy in Treating Patients With Locally Advanced, Locally Recurrent, or Metastatic Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed adenocarcinoma of the colon or rectum Locally advanced, locally recurrent, or metastatic disease Not curable by surgery and/or not amenable to radiotherapy with curative intent Histological or cytological confirmation of metastatic cancer not required for patients with prior surgically resected colorectal cancer if more than 5 years elapsed between primary surgery and development of metastatic disease OR if primary cancer was stage I or II Prior adjuvant therapy with fluorouracil or immunotherapy for resected stage II, III, or IV disease allowed Measurable disease No known brain metastases PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-1 Life expectancy: More than 12 weeks Hematopoietic: WBC at least 3,000/mm^3 Absolute neutrophil count at least 1,500/mm^3 Platelet count at least 100,000/mm^3 Hepatic: Bilirubin normal AST/ALT no greater than 5 times upper limit of normal Renal: Creatinine normal Cardiovascular: No uncontrolled high blood pressure No unstable angina No symptomatic congestive heart failure No myocardial infarction within the past 6 months No serious uncontrolled cardiac arrhythmia No New York Heart Association class III or IV heart disease Other: No active or uncontrolled infection No predisposing colonic or small bowel disorders with uncontrolled symptoms as indicated by more than 3 loose stools daily in patients without a colostomy or ileostomy No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or adequately treated noninvasive carcinomas No other concurrent medical or psychiatric condition that would preclude study Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: At least 12 months since prior immunotherapy Chemotherapy: At least 12 months since prior fluorouracil No prior chemotherapy for advanced colorectal cancer No prior irinotecan Radiotherapy: No prior radiotherapy to more than 15% of bone marrow At least 4 weeks since prior major radiotherapy (e.g., chest or bone palliative radiotherapy) No concurrent radiotherapy Surgery: At least 4 weeks since prior major surgery (e.g., laparotomy) and recovered At least 2 weeks since prior minor surgery and recovered No concurrent ophthalmic surgery Other: No prior ZD 1839 No other concurrent investigational or commercial agents or therapies for malignancy No concurrent combination antiretroviral therapy for HIV No concurrent oral retinoids No concurrent prochlorperazine on day of irinotecan administration