Overview of Adjuvant and Neoadjuvant Therapy for Resectable Gastric Cancer in the East

This review presents the current status of adjuvant and neoadjuvant treatment options for primary resectable gastric cancer in the East, with updated data from recent studies. Marked disparities between the East and the West in standard surgical procedures (D2 vs. D1/0 lymphadenectomy) and their outcomes result in significant geographical variation in preferred adjuvant treatments. Currently, oral fluoropyrimidine-based postoperative adjuvant chemotherapy, 1 year of S-1 chemotherapy, or capecitabine plus oxaliplatin for 6 months are the standards of care after curative resection with D2 lymphadenectomy for stage II/III gastric cancer in the East, though there is still some room for improvement. The role of postoperative adjuvant chemoradiotherapy (CRT) following curative D2 gastrectomy has long been debated in the East. However, the first prospective randomized controlled trial comparing CRT with chemotherapy alone failed to demonstrate a survival benefit, thus further studies are required. Chemotherapy has been pursued as a neoadjuvant approach in East Asia because of a rare locoregional recurrence after curative D2 gastrectomy. Locally advanced, marginally resectable gastric cancer with poor prognosis, such as large type 3 or 4 tumors, para-aortic and/or bulky nodal disease, and serosa-positive gastric cancer, is the main target of neoadjuvant chemotherapy. Promising efficacy has been demonstrated in several phase II studies with the safe use of D2 or more extended surgery following neoadjuvant chemotherapy. Although the results of ongoing phase III trials are awaited, Asian findings could be relevant and generalizable to other regions when D2 surgery is performed by experienced surgeons.