Clinical treatment score post-5 years and survival benefit from extended endocrine therapy for breast cancer patients under and over 50 years of age.

Background: This study aimed to determine whether clinical treatment score post-5 years (CTS5) could predict the clinical benefits of extended endocrine therapy (ExET) in young and old patients.

Methods: We reviewed 2495 hormone receptor-positive breast cancer patients treated between 2001 and 2012 who were free from recurrence or death during the 5 years post-surgery in South Korea. The cohort was analyzed separately based on age (≤ 50 years and > 50 years). Multivariable analysis was conducted, and a cutoff of CTS5 < 3.13 was defined as the low group and CTS5 ≥ 3.13 as the intermediate/high (int/high) group.

Results: The median follow-up duration was 115 months. Regardless of young and old age at diagnosis, the low group displayed considerably enhanced disease-free survival. Multivariate analysis revealed that the low group emerged as an independent and favorable prognostic factor for disease-free survival after adjusting for ExET use and prognostic parameters. Patients in the low group demonstrated a trend toward improved overall survival compared to those in the int/high group, reaching marginal statistical significance. ExET use demonstrated a significant correlation with improved disease-free survival, particularly in patients aged ≤ 50 years.

Conclusions: ExET should be considered in premenopausal and postmenopausal breast cancer patients with high CTS5 levels.