BackgroundAlthough the multidisciplinary-collaborated team approach in cancer treatment has recently become popular, prospectively evaluated evidence is limited. We started a multidisciplinary-collaborated cancer support team (MCST) to facilitate cooperation across multidisciplinary medical staff in our hospital and established clinical evidence of supportive care. This study aimed to prospectively evaluate the clinical activity and effect of MCST in patients with gastrointestinal cancer receiving chemotherapy.MethodsThis is a single-center, single-arm, observational study. Patients with gastrointestinal cancer scheduled to receive chemotherapy are enrolled and supported by the MCST. The primary endpoints are the number of interventions by medical staff and the number of patients who showed improvement in side effects. The secondary endpoints are the severity of side effects, medical expenses, number of consultations, the acceptance rate of prescription recommendations, adjuvant chemotherapy completion rates, dose intensity, and time required for co-medical intervention. In addition, medical staff and attending physicians evaluate all adverse events.DiscussionThis study is expected to contribute to establishing new cancer-supportive care teams for patients with gastrointestinal cancer receiving chemotherapy and those with cancer receiving chemotherapy.Trial registrationThis trial was registered in the Japan Registry of Clinical Trials (jRCT) as jRCT1030220495.The date of first registration, 29/11/2022,https://jrct.niph.go.jp/searchSupplementary InformationThe online version contains supplementary material available at 10.1186/s12876-023-02849-6.