The primary study end-point was overall survival and the secondary endpoints were relapse free survival and safety. Both primary and secondary efficacy objectives of the study have been met. The reduction of the relative risk of relapse with S-1 was 38%. For all randomized patients, the 3 year relapse free survival was 72.2% in the S-1 arm and 60.1% for surgery alone.
The results indicate that for all patients overall survival at 3-years was 80.5% for patients receiving S-1 and 70.1% for patients undergoing surgery alone. The most common grade 3 or 4 adverse reactions for nausea, vomiting, diarrhea, anorexia and hematological reactions were below or equal to 6%.
S-1 is currently used in Japan for the treatment of gastric, colorectal, head and neck, non-small cell lung, breast and pancreas cancers. In the US, Europe and other countries, the product is in phase III clinical development.