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

Background: Pretreatment endocrine symptoms in premenopausal patients might be considered as a potential marker of poor prognosis. We conducted a cohort study to evaluate the association between endocrine symptoms prior to treatment and recurrence-free survival (RFS) among premenopausal patients with breast cancer aged ⩽40 years. Methods: Data were obtained from a prospective cohort study (NCT03131089) conducted at the Samsung Medical Center from 2013 to 2021. We included patients aged ⩽40 years who had been diagnosed with breast cancer. The primary outcome measure was RFS. Endocrine symptoms were measured using the Functional Assessment of Cancer Therapy – Endocrine Symptoms (FACT-ES). We also calculated the hazard ratio (HR) for recurrence or all-cause mortality by comparing the tertiles of the FACT-ES score at diagnosis. Results: Among the 977 participants, the mean (standard deviation) age was 35.3 (3.9) years. At diagnosis, 17.2% of the patients had at least one severe endocrine symptom. During 3512 person-years of follow-up, the high symptom group had a worse RFS than the low-symptom group [HR = 2.05; 95% confidence interval (CI) = 1.19–3.54]. In particular, hot flashes (HR = 5.59; 95% CI = 1.96–15.93) and breast sensitivity (HR = 1.82; 95% CI = 1.00–3.32) were associated with reduced RFS. Conclusion: Close monitoring of pretreatment endocrine symptoms may be important in patients diagnosed with breast cancer at a young age.