胃癌化学療法の新たな展開

Recent Advances in Chemotherapy for Advanced Gastric Cancer

　日本においては，切除不能進行胃癌に対する化学療法は，従来はpalliative careとして認識されており，治療法についても，“医者のさじ加減”が優先され，EBMとはほど遠いものであった．近年，切除不能進行胃癌例に対する化学療法は，best supportive careと比べて生存期間の延長が証明され，化学療法の考え方の変化をもたらしてはいるが，効果は不十分であり，5-FU単剤を越える標準的治療法は確立していない．new agentとしてのCPT-11は，CDDPやMMCとの併用により60％前後，経口剤S-1も単剤で45％，CDDPとの併用で76％と従来の併用治療法に比べても非常に高い奏効率を認めている．最終的には，5FU単剤と比較した第III相比較試験(JCOGで進行中)での生存期間での評価が必要である．さらに，胃癌に対しても生物学的・薬物動態的特性に基づいた治療戦略が可能となり始めていると同時に分子生物学的マーカーや分子標的の見地に立った治療法の確立に期待が持たれている．

　In Japan, the mortality rate of gastric cancer has been decreased by the spread of diagnosis and surgical treatment for early gastric and the decrease of gastric cancer frequency. Although chemotherapy for advanced gastric cancer contributes to survival benefit as compared to best supportive care based on randomized controlled studies, no standard regimens which are superior to 5-fluorouracil (5-FU) alone in survival benefit have been demonstrated yet. Recent progress of new anti-cancer drugs such as irinotecan(CPT-11)and S-1 have provided higher response rates than previous chemotherapeutic regimens. CPT-11 in combination with cisplatin or with mitomycin-C yielded a response rate of nearly 60 ％ for chemo-naive patients and S-1 also provided a response rate of 45 ％ in a single agent study and 76 ％ in combination study with cisplatin. Two randomized controlled trials (5-FU alone vs. CPT-11＋CDDP vs. S-1 alone supported by Japan Clinical Oncology Group (JCOG) and S-1 vs. S-1＋CDDP sponsored by a drug company) for patients with advanced gastric cancer has been held to clarify whether these new regimens improve survival outcomes.