[Results of Neoadjuvant Chemotherapy with S-1 plus CDDP for Gastric Cancer-The Number of Therapeutic Coursers and Therapeutic Effects]

Neoadjuvant chemotherapy(NAC)with S-1 plus CDDP(SP)followed by gastrectomy has been used for the treatment of patients with locally advanced gastric cancer. We examined the number of treatment courses, histologic effects, ypStage, and prognosis to estimate the utility and define the best treatment course of SP NAC. The patients were divided into 1 course(A: 54 cases), 2 courses(B: 50 cases), and incomplete first course(C: 12 cases). The rates of Grade 2 or more in histological effect were 24.1% in group A, 34.0% in B, and 0% in C. Four patients achieved pathological CR(1 case in group A and 3 cases in group B). The pathological response by NAC was more effective in group B than in group A. In down-staging cases by NAC, survival curves were obtained according to ypStage. The 5-year survival rates in R0 cases were 67.0%in the effective therapeutic group and 51.0%in the non-effective group; the results being significantly different. According to the number of therapeutic courses of NAC, the 5-year survival rates were 57.9% in group A, 65.2% in group B, and 20.0% in group C, demonstrating a significantly better prognosis in group B. Although the pathological response appeared in 1 course, it was significant in 2 courses of NAC. The results indicate that the completion of at least 2 courses of NAC are necessary in locally advanced gastric cancer.