免疫チェックポイント阻害剤の登場によって肝癌診療が変革期を迎えると共に，次世代シークエンサーや空間的解析技術の進歩により，肝癌研究も新たなステージを迎えている．癌の全容解明には，癌細胞の分子異常（ゲノム・エピゲノム）や形質変化に加えて，癌微小環境における間質細胞（免疫細胞や線維芽細胞，血管内皮細胞など）の機能や細胞間相互作用を包括的に理解することが不可欠である．近年，癌免疫微小環境の違いが，治療後の再発や生存，薬物療法の効果にも強く影響することが明らかになる一方，様々な局所治療や薬物治療自体が癌免疫微小環境を変容させる可能性も示されている．治療選択肢の多い肝癌診療においては，癌免疫微小環境のさらなる理解とそれに基づいたバイオマーカーの開発が個別化医療の実現に必要と考えられる．そこで本シンポジウムでは，肝癌の免疫微小環境の理解や個別化医療への応用に寄与する最新の研究成果をご発表いただき，今後の展望や課題を議論したい．

The advent of immune checkpoint inhibitors has transformed liver cancer treatment, while advancements in next-generation sequencing and spatial analysis are pushing research into a new era. To fully elucidate the complexities of cancer, it is essential to comprehensively grasp not only the molecular abnormalities (genomic and epigenomic) and phenotypic changes of cancer cells but also the functions and intercellular interactions of stromal cells (such as immune cells, fibroblasts, and vascular endothelial cells) within the tumor microenvironment. In recent years, it has become evident that differences in the tumor immune microenvironment significantly affect recurrence, survival, and efficacy of pharmacotherapy, while various locoregional therapies and pharmacotherapy may alter the tumor immune microenvironment. Given the many treatment options in liver cancer, understanding the immune microenvironment and developing biomarkers are key to achieving personalized medicine. In this symposium, we hope to have the latest research on the liver tumor immune microenvironment and its application to personalized treatment, while discussing future challenges and opportunities.