DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed colorectal adenocarcinoma

  • Metastatic or locally advanced disease
  • Not amenable to curative therapy
• Documentation of disease progression within the past 6 months
• Previously treated with fluoropyrimidine- and irinotecan-based chemotherapy (including capecitabine) administered either concurrently (no more than 2 regimens) or sequentially (no more than 3 regimens) for advanced disease

• At least 1 unidimensionally measurable lesion

  • At least 20 mm by conventional techniques OR at least 10 mm by spiral CT scan
• No known brain metastases

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2 OR
• Karnofsky 60-100%

Life expectancy:

• More than 12 weeks

Hematopoietic:

• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• AST/ALT no greater than 3 times ULN (5 times ULN if liver metastasis present)

Renal:

• Creatinine no greater than 1.5 times ULN OR
• Creatinine clearance at least 60 mL/min

Cardiovascular:

• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia

Ophthalmic:

• No significant ophthalmic conditions, including:

  • Severe dry-eye syndrome
  • Keratoconjunctivitis sicca
  • Sjogren's syndrome
  • Severe-exposure keratopathy
  • Disorders that may increase the risk for epithelium-related complications (e.g., bullous keratopathy, aniridia, severe chemical burns, or neutrophilic keratitis)

Other:

• Able to take oral gefitinib
• No other uncontrolled concurrent illness
• No ongoing or active infection
• No psychiatric illness or social situation that would preclude study participation
• No prior gastrointestinal disorders (e.g., malabsorption syndrome)
• No prior allergic reactions attributed to compounds of similar chemical or biological composition to gefitinib
• No other prior malignancy except carcinoma in situ of the cervix, nonmelanoma skin cancer, or other cancer from which the patient has been free of evident disease for more than 5 years and/or has less than a 20-30% estimated likelihood of recurrence
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• See Disease Characteristics
• At least 30 days since prior chemotherapy and recovered

Endocrine therapy:

• Not specified

Radiotherapy:

• Not specified

Surgery:

• No prior gastric resection

Other:

• No other prior therapy for advanced disease
• No concurrent combination antiretroviral therapy for HIV-positive patients
• No other concurrent investigational or commercial agents or therapies for the malignancy