DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed adenocarcinoma of the stomach* or gastroesophageal (GE) junction

  • GE junction tumors include esophageal tumors arising 5 cm from the anatomic GE junction or in the gastric cardia
  • Locally advanced (i.e., unresectable) or metastatic disease NOTE: *Gastric stratum temporarily closed to accrual as of 03/01/2003

• Unidimensionally measurable disease

  • Target lesion must not be in previously irradiated field unless there is documentation of clear progression
• No known brain metastases

PATIENT CHARACTERISTICS:

Age:

• Not specified

Performance status:

• Zubrod 0-1

Life expectancy:

• Not specified

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)
• SGOT or SGPT no greater than 1.5 times ULN (5 times ULN if liver metastases present)

Renal:

• Creatinine no greater than 2 times ULN

Cardiovascular:

• No recent myocardial infarction
• No unstable angina
• No life-threatening arrhythmia

Gastrointestinal:

• No gastrointestinal tract disease resulting in an inability to take oral medication or a requirement for IV alimentation
• No active peptic ulcer disease
• Must be able to swallow and/or receive enteral medications via gastrostomy feeding tube
• No intractable nausea or vomiting

Ophthalmic:

• No history of corneal disease, including:

  • Dry eye syndrome or Sjögren's syndrome
  • Keratoconjunctivitis sicca
  • Exposure keratopathy
  • Fuch's dystrophy
  • Other active disorders of the cornea

Other:

• HIV negative
• No active or uncontrolled infection
• No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or adequately treated stage I or II cancer currently in complete remission
• No severe psychiatric disorders
• Not pregnant or nursing
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No prior biologic therapy
• No concurrent anticancer immunotherapy

Chemotherapy:

• No prior chemotherapy for advanced or metastatic gastric cancer
• At least 8 weeks since prior adjuvant chemotherapy or chemotherapy given as a radiosensitizer and recovered
• No concurrent anticancer chemotherapy

Endocrine therapy:

• No concurrent anticancer hormonal therapy

Radiotherapy:

• See Disease Characteristics
• At least 4 weeks since prior radiotherapy and recovered
• No concurrent anticancer radiotherapy

Surgery:

• At least 4 weeks since prior surgical procedure for stomach* or GE cancer and recovered
• No prior surgical procedures that would affect absorption NOTE: *Gastric stratum temporarily closed to accrual as of 03/01/2003

Other:

• No prior investigational drugs
• No concurrent combination antiretroviral therapy for HIV-positive patients
• No other concurrent anticancer therapy