Dr Shitara is an active member of ASCO and ESMO. He is also a member of the Japanese Society of Internal Medicine, the Japanese Society of Medical Oncology (JSMO), the Japanese Society of Clinical Oncology (JSCO), the Japanese Gastric Cancer Association, Protocol Review Committee of Japanese Clinical Oncology Group (JCOG), West Japanese Oncology Group (WJOG). He also acts as one of the organising members for Japanese gastric cancer treatment guidelines.

Main research interests include development of new anti-cancer agents, optimal chemotherapy regimen for gastrointestinal cancer, and translational research. He is the primary investigator or study coordinator of several sponsor initiated trials or investigator initiated trials for gastric or colorectal cancer: He act as a steering committee members of 5 global studies in the field of GI cancers. He also acts as a study coordinator of the Nationwide Cancer Genome Screening Projects for Gastrointestinal Cancer in Japan (SCRUM-Japan GI-SCREEN).

He has reported 120 peer review publications which include approximately 80 articles as 1st author or corresponding author in these fields.