Neoadjuvant chemotherapy for gastric cancer in Japan: a standing position by comparing with adjuvant chemotherapy.

Adjuvant chemotherapy aims to eradicate micrometastatic tumor cells before and after curative surgery. Many Phase III trials have been conducted to study the efficacy of postoperative adjuvant chemotherapy; however, most trials have failed to show any survival benefit because of their low statistical power and/or poor patient compliance. Since 2000, two pivotal Phase III trials, the ACTS-GC and the CLASSIC, have demonstrated the efficacy of postoperative adjuvant chemotherapy following D2 gastrectomy. Although treatment with S-1 for 1 year or combination therapy with capecitabine and oxaliplatin for 6 months is effective, more intensive chemotherapy is necessary to further improve the survival rates. In Europe, two Phase III trials, the MAGIC and the FNCLCC/FFCD, have produced results that strongly suggest that neoadjuvant chemotherapy is beneficial. The advantages of neoadjuvant chemotherapy include a high rate of R0 resection, tumor regression, high compliance and the avoidance of unnecessary surgery. The disadvantage of neoadjuvant chemotherapy is over-diagnosis. In Japan, the Japan Clinical Oncology Group has conducted several clinical trials using neoadjuvant chemotherapy to target extensive nodal disease and/or scirrhous carcinomas. The optimal courses and regimens of neoadjuvant chemotherapy should, therefore, be clarified in the future.