Validation of CTS5 model in large-scale breast cancer population and the impact of menopausal and HER2 status on its prognostic value

Clinical Treatment Score post-5 years (CTS5) is a promising prognostic tool to evaluate late recurrence risk for breast cancer. Our study aimed to validate its prognostic value in large-scale population and explore the impact of menopausal and HER2 status on CTS5 model. We performed a retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER) database. Survival analyses were conducted to assess the prognostic value of CTS5 in different breast cancer subgroups in terms of overall survival (OS) and breast cancer specific survival (BCSS) after five years. A total of 23,168 breast cancer patients with positive hormone receptor (HoR) were enrolled. Postmenopausal and premenopausal patients were 13,686 and 9,482, respectively. Taking CTS5 score as a continuous variable, it had significant positive correlation with poor prognosis beyond five years in both postmenopausal and premenopausal subgroups. Nevertheless, for HER2+ postmenopausal patients, the model has less effective prognostic value on long-term BCSS [HR1.177 (95%CI 0.960–1.443), p = 0.117]. Using CTS5 score as a categorical variable, HER2- patients with high-risk level revealed significant poor survival in terms of both BCSS and OS, irrespective of menopausal status. Our study showed the CTS5 model could be a useful prognostic tool for predict long-term survival in HoR+/HER2- patients. And further large-scale studies are warranted to assess its prognostic value for HER2+ patients and develop novel prediction model for late recurrence risk estimation.