The division of Gastrointestinal Medical Oncology focuses on the development of new drugs and establishment of standard chemotherapy regimens including multimodality treatment with surgery and/or radiotherapy for advanced esophageal/gastric/colorectal cancers, gastrointestinal stromal tumor, and other gastrointestinal (GI) malignancies. The team does not only participate in many industry-sponsored trials but also conduct investigator-initiated trials, which are associated with translational research, in collaboration with many clinicians and basic researchers in Japan, Asia, and worldwide. Recently, the team has investigated biomarkers using pretreatment tumor and blood samples, including circulating tumor cell and cell-free DNA. Because easy access to tumor samples by endoscopy is a strong point in GI malignancy, the team is now preceding to translational research using repeated biopsy samples after administering investigational drugs.