Current status of perioperative chemotherapy for locally advanced gastric cancer and JCOG perspectives.

Perioperative treatment for locally advanced gastric cancer has been inconsistent between Japan and the Western countries. In Japan, D2 gastrectomy followed by adjuvant chemotherapy is regarded as standard treatment, while neoadjuvant or perioperative chemotherapy is considered to be a standard in the Western countries. Stomach Cancer Study Group of Japan Clinical Oncology Group (JCOG) has conducted many perioperative chemotherapy trials. After the publishing of positive results of ACTS-GC trial, stage-specific adjuvant chemotherapy protocols are planned. JCOG1104 was conducted as to demonstrate the non-inferiority of four courses of S-1 to standard eight courses of S-1, because the efficacy of S-1 appears to be sufficient in stage II. The trial failed to demonstrate the non-inferiority of four courses of S-1. S-1 for 1 year is still recognized to be a standard for stage II gastric cancer. For stage III, studies with more intensive treatments were planned as the efficacy of S-1 monotherapy seems to be insufficient. As in the Western countries, JCOG planned the perioperative chemotherapy. However, the clinical staging is a serious issue to select optimal patients for perioperative chemotherapy. JCOG conducted a prospective cohort study to evaluate the validity of clinical staging in JCOG1302A. From the results of this study, cT3-4 and cN1-3 are selected as optimal candidate for perioperative chemotherapy. JCOG1509 was conducted to demonstrate the superiority of perioperative chemotherapy to adjuvant chemotherapy in these cohorts. Perioperative chemotherapy for marginally resectable tumours such as linitis plastica or extensive nodal disease and special type of cancer like HER2 positive are also conducted.