Prospective Observational Study to Identify Factors Influencing Adverse Symptoms Associated With Endocrine Therapy in Breast Cancer Patients, a Protocol: Contribution of Japanese Traditional Medicine to Quality of Life and Work Productivity

ABSTRACT Aim Endocrine therapy causes side effects ( SEs ) such as hot flushes, joint stiffness, and psychological disorders in patients with breast cancer ( BC ). To address these symptoms, Japanese traditional (Kampo) medicine will be used as treatment. This study aims to identify factors that influence the SE associated with endocrine therapy in patients with BC and evaluate an association with symptom relief of Kampo medicine in alleviating the SE . Methods A prospective observational study will be conducted from May 1, 2024 to March 31, 2027, including patients aged > 20 years with BC (clinical stages 0 to III ) experiencing SE from endocrine therapy. The SE will be rated on a numerical rating scale ( NRS ) from 0 (no symptom) to 10 (worst symptom). Treatment with Kampo or conventional medicines will depend on the patient preference. Prescriptions will be designed to suit patient's symptoms and physical findings, following the principles of Kampo medicine. Data on the patient's background, physical examination, routine clinical examination, and medication will be collected. The assessment—including symptom severity by NRS , quality of life ( QOL ) by EuroQol 5 dimensions 5‐level ( EQ ‐ 5D ‐ 5L ) and Functional Assessment of Cancer Therapy‐Breast ( FACT ‐B), and work productivity and activity impairment by the Work Productivity and Activity Impairment‐General Health ( WPAI ‐ GH )—will be conducted using an electronic patient‐reported outcome system. This study protocol has been approved by the Ethics Committee of our university. Conclusion By demonstrating an association with symptom relief of Kampo medicine in managing SEs of endocrine therapy for BC, this study aims to improve patients' QOL and work productivity. Trial Registration: This study was registered in the University Hospital Medical Information Network Center (UMIN000054353)