Overview of adjuvant therapy for resected gastric cancer: differences in Japan and the United States.

Survival in adjuvant chemotherapy following resected gastric cancer has been studied by both Japanese and Western investigators using varied chemotherapy regimens in different target patients. Gastrectomy with D2 lymphadenectomy is the standard in Japan, and trials of adjuvant therapy in these patients have shown no survival advantages over surgery alone. In the United States, where 5-year survival rates in patients with gastric cancer are much lower following potentially curative surgery, adjuvant therapy has shown a survival benefit. The differences observed in these trials may result from the additional experience that Japanese surgeons have gained because of the higher incidence of gastric cancer there, or because of this increased incidence, there are more stringent screening guidelines in place and these cancers are possibly being diagnosed at an earlier stage. The Japanese viewpoint on the use of adjuvant therapy in patients with gastric cancer following potentially curative resection is that the quality of surgery, including diagnostic and pathologic procedures, is a more important prognostic factor than adjuvant chemotherapy. Also, they have determined from previously conducted clinical trials that patients with stage 1-2 tumors should be excluded from the target populations of randomized trials. Until the results of INT-0116 became available, there had been no improvement, or only marginal improvement, in overall or disease-free survival for patients receiving adjuvant chemotherapy following gastric cancer resection in the United States and Europe.