The basic and translational research undertaken in the Exploratory Oncology Research & Clinical Trial Center (EPOC) and the National Cancer Center Hospital East (NCCHE) is aimed toward future clinical use. To develop anti-cancer drugs based on a novel concept or a novel imaging technology, animal experiments are necessary. Not only cell line derived xenograft (CDX) models in which human cancer cells are transplanted into immunodeficient mice, but also spontaneous cancer models using genetically modified mice and patient-derived xenograft (PDX) models using human cancer tissue which are reproduced the cancer microenvironment, are used in the animal facility of the EPOC. Developments of novel surgical and endoscopic instruments using experimental pigs are also conducted in the animal facility. The Section of Experimental Animals supports the animal experiments conducted in the EPOC and the NCCHE.