胃癌の術後補助化学療法と術前化学療法―有効性の検証

Post-operative and Preoperative Adjuvant Chemotherapy for Gastric Cancer Inspection of Efficacy

要旨　欧米では術後補助化学療法に関しメタアナリシスにて有効性が示されたが，比較的大規模なRCTでも単一の試験においては手術単独に対する胃癌補助化学療法の優位性が証明されていない．本邦でも漿膜浸潤陰性および漿膜浸潤陽性症例を対象としたJCOG臨床試験にて，術後補助化学療法の有効性は検証されなかった．したがって，現時点では標準治療となるべき特定の術後補助化学療法を推奨することはできない．術前治療に関しては，米国では根治術が困難な高度進行胃癌に対し術前放射線化学療法の有効性が示唆され，欧州ではMAGIC trial後，術前化学療法の有効性を検証する大規模第III相試験が始まっている．本邦でも新薬の出現，強力な術前化学療法により，down staging，MSTの改善は得られてきている．特にTS-1＋CDDP療法は有害事象が比較的軽度，奏効率が高率で，期待できる治療法である．新規臨床試験としては，術後のコンプライアンスの低さを克服する点で，術前投与にパラダイムシフトする傾向がある．

　A relatively large scale randomized clinical trial (RCT) could not prove a favorable survival advantage for patients with gastric cancer (GC), though several meta-analyses in Western countries revealed evidence of the survival benefit of postoperative adjuvant chemotherapy (CTx). In Japan, JCOG' RCTs of adjuvant chemotherapy for serosa-negative or serosa-positive GC after curative surgery hasn't been able to improve the survival benefit. Therefore, there is no recommending standard therapy for postoperative adjuvant chemotherapy (CTx). As a preoperative adjuvant CTx, preoperative radiochemotherapy for initially incurable advanced GC was proved in the USA. After the MAGIC trial in Europe, large scale phase III trials have been on-going in order to prove the advantage of preoperative adjuvant CTx. Even in Japan, the appearance of new anticancer drugs and intensive chemotherapy regimens could reduce staging and improvement of survival. TS-1＋CDDP, which has confirmed feasibility and sufficient efficacy, is one of the most expected regimens. There seems to be a tendency towards a paradigm shift from postoperative to preoperative CTx as new RCTs, in order to avoid the low compliance of postoperative adjuvant CTx.