Pretreatment endocrine symptoms and recurrence-free survival among young premenopausal patients with breast cancer: a prospective cohort study.

"The authors declare that there is no conflict of interest."

"Funding: The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by Future Medicine 20*30 Project of the Samsung Medical Center [grant numbers: SMX1210831]."

"Data were obtained from a prospective cohort study of young patients with breast cancer (40 years old or younger) (Samsung Medical Center-Young Breast Cancer Registry, NCT03131089) to identify comprehensive clinicopathological features and long-term outcomes of this patient group. Patients were recruited at initial visit for their initial treatment at outpatient clinics or inpatient rooms at the Samsung Medical Center, Seoul, Korea in May 2013. For this study, we included premenopausal patients (n = 977) who were diagnosed with breast cancer between May 2013 and April 2021 and who had completed the endocrine symptom questionnaire [Functional Assessment of Cancer Therapy–Endocrine Symptoms (FACT-ES)] before any type of treatment including surgery and neoadjuvant treatment."