Although
neoadjuvant chemotherapy has been recognized as an important option to improve the clinical outcome of patients with advanced gastric
carcinoma, the precise histological effects of
neoadjuvant chemotherapy on the primary and metastatic foci have not well been documented. The aim of the present study was thus to evaluate histological effects of S-1-based
neoadjuvant chemotherapy on the resected specimens of gastric
carcinoma and regional lymph nodes, and primarily to focus on the histology of the cases showing complete regression of the primary
cancer cells. A total of 164 patients received
neoadjuvant chemotherapy with the combination of S-1 (80 to 120 mg/body/day for 3 weeks) and
cisplatin (35 to 60 mg/m2 on day 8). One course of the regimen was completed in 5 weeks and the next course was started after 2 weeks. A total of 9 patients who showed complete regression of the primary
gastric cancer were subjects of the study. A total of 77 cases (46.9%) responded to the
neoadjuvant chemotherapy and 9 cases (5.5%) showed a complete regression of the primary gastric
carcinoma. Three out of 9 cases had remnant
cancer cells in the metastatic foci; 1 in the liver and 2 in the regional lymph nodes. Five of 9 cases were solid-type poorly-differentiated
adenocarcinoma (por1), and the incidence of responders was the highest in patients with por1. A total of 8 cases were alive and the mean postoperative survival was 612±192 days. One patient died 518 days after
gastrectomy associated with hepatic resection. S-1-based
neoadjuvant chemotherapy has significant histological effects on gastric
carcinoma and metastatic foci, which may further improve long-term clinical outcome in patients with advanced gastric
carcinoma.