DISEASE CHARACTERISTICS:

• Histologically or cytologically proven unresectable, locally advanced or metastatic adenocarcinoma of the stomach or gastroesophageal junction

• No known brain metastases

  • Negative brain imaging required for neurologic signs and symptoms

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Zubrod 0-1

Life expectancy:

• Not specified

Hematopoietic:

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

Hepatic:

• Bilirubin no greater than upper limit of normal (ULN)
• SGOT or SGPT no greater than 1.5 times ULN (5 times ULN if liver tumor present)

Renal:

• Creatinine no greater than ULN

Other:

• Not pregnant or nursing
• Fertile patients must use effective contraception
• Must be able to swallow oral medication
• No AIDS syndrome or HIV-associated complex
• 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 in complete remission

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No prior biologic therapy
• No concurrent biologic therapy

Chemotherapy:

• No prior chemotherapy for advanced or metastatic gastric cancer
• At least 6 months since prior chemotherapy as adjuvant or radiation sensitizer

Endocrine therapy:

• Not specified

Radiotherapy:

• At least 1 month since prior radiotherapy and recovered
• No concurrent radiotherapy

Surgery:

• At least 3 weeks since prior major surgical resection of intra-abdominal organs and recovered