The main purpose of this trial is to determine how well patients with gastric or gastroesophageal junction adenocarcinoma respond to chemotherapy with epirubicin, cisplatin and 5-fluorouracil followed by continuous infusion 5-fluorouracil chemotherapy given along with radiation therapy.

• Patients will receive epirubicin and cisplatin intravenously on day 1 of treatment. 5-fluorouracil will be given continuously by intravenous infusion bia a portable ambulatory pump (CADD pump) for 21 days. This cycle of chemotherapy will take 21 days (3 weeks). Once it is complete there will be one week without therapy.
• Once the patient has recovered from any side-effects from the chemotherapy they will start the combination chemoradiation therapy, 5-fluorouracil and radiation. The radiation will be directed to the upper abdomen in the area where the stomach tumor has been located. The radiation therapy will be given five days a week for a total of five weeks. During these five weeks patients will receive 5-fluorouracil continuously by CADD pump.
• After completion of combination chemoradiation therapy there will be a three to four week rest period followed by 2 additional chemotherapy cycles identical to the first chemotherapy cycle.
• The following tests and procedures will be performed: physical examination every 4 weeks except during the chemoradiation therapy when it will be done weekly; blood tests every week during chemotherapy and chemoradiation; CT scans and chest x-rays done before therapy, at the end of therapy, and yearly for 2 years; noninvasive testing to evaluate kidney function before starting the study.
• The program of chemotherapy and radiation therapy will last approximately 30 weeks. After all treatment is completed, patients will return for physical examinations and blood tests every 3 months for 3 years; then every 6 months for 2 years.

Inclusion Criteria:

• Patients must have adenocarcinoma of the stomach or gastroesophageal junction. Adenocarcinomas of the esophagus that are not involving the gastroesophageal junction are not eligible.
• Patients must have had en bloc resection of all known tumor and be at high risk for later failure. The surgical resection must have been done with a curative intent. The stomach, lver, peritoneum, omentum and regional lymph nodes must be evaluated and all identified tumor be resected.
• The surgical specimen, and the pathologic analysis thereof, must be adequate for TNM staging.
• Treatment must begin between day 20 and day 56 after the gastrectomy.
• ECOG performance status of 0,1 or 2
• ANC > 1,500/ul and platelet count >100,000/ul
• Serum creatinine < 1.5mg/dl
• Total bilirubin < 2.0 mg/dl and AST < 3 x ULN
• Estimated caloric intake of 1500K calories per day or greater

Exclusion Criteria:

• Known unresected cancer, microscopic evidence of tumor at the line of resection, noncontiguous resection of tumor, or M1 disease
• Ascites, peritoneal seeding, liver metastasis or extra-abdominal metastasis
• Prior malignancy except for adequately treated basal cell or squamous cell skin cancer, non-invasive carcinoma in situ which has been fully resected, or other cancer for which the patient has been disease free for five years
• Previous chemotherapy or radiotherapy
• Active infectious process
• Pregnant or lactating women
• Myocardial infarction in the past 6 months or prior history of congestive heart failure or significant valvular heart disease
• Uncontrolled serious medical or psychiatric condition
• Grade 2 or greater peripheral neuropathy at baseline