Protocol for the ASTRO study (SSOP-01): a multicentre prospective cohort study investigating adverse events based on electronic patient-reported outcomes in patients with breast cancer after adjuvant chemotherapy

INTRODUCTION: Symptom-related adverse events associated with perioperative chemotherapy in patients with breast cancer include short-term adverse events such as nausea and vomiting. However, changes in the severity and duration of prolonged symptom-related adverse events have not been fully investigated. We present a protocol of a study that aims to clarify the prevalence of symptom-related adverse events in patients with breast cancer 1 year after neoadjuvant or adjuvant chemotherapy using an electronic patient-reported outcomes (ePRO) system. METHODS AND ANALYSIS: This multicentre prospective observational cohort study will include patients with breast cancer who have received preoperative or postoperative adjuvant chemotherapy. The final injection date of the cytotoxic agent will be the study initiation date. Patients will report every 2 weeks from the initiation date to 12 weeks and every 4 weeks from 12 weeks to 1 year, and they can enter this information into the ePRO system from anywhere. The primary outcome will be the prevalence of symptom-related adverse events according to the ePRO system 1 year after the date of the last injection of the cytotoxic drug used in neoadjuvant or adjuvant chemotherapy for breast cancer. To increase multi-institutional enrolment, two cohorts will be included. Cohort 1 will comprise patients with acquisition of baseline patient information regarding preoperative chemotherapy and presurgery characteristics. Cohort 2 will comprise patients without acquisition of baseline patient information. The target sample size is ≥250 per year. ETHICS AND DISSEMINATION: The study protocol has been approved by the ethics committee at each participating institution. The results will be presented at major national and international conferences and submitted to peer-reviewed journals. TRIAL STATUS: Registration was started in October 2021. By August 2022, a total of 132 participants were enrolled. Follow-up will be continued through December 2024. TRIAL REGISTRATION NUMBER: UMIN000045422.