OBJECTIVES: I. Evaluate the efficacy and toxicity of neoadjuvant cisplatin/fluorouracil (CDDP/5-FU) followed by surgery followed by adjuvant intraperitoneal floxuridine/leucovorin in patients with high-risk gastric cancer. II. Assess the quality of life and cost-benefit ratio associated with this treatment. III. Evaluate the sensitivity, specificity, and overall staging accuracy of laparoscopy with or without laparoscopic ultrasound in predicting the resectability rate (with and without neoadjuvant CDDP/5-FU), response to chemotherapy, and accuracy when compared to pathologic findings. IV. Correlate the presence of mutated vs. wild-type p53 suppressor oncogenes in endoscopic biopsies and resected tumor specimens with clinical outcome (defined as downstaging, failure pattern, and disease-free and overall survival) in patients treated with and without neoadjuvant CDDP/5-FU.