Assessment of the HFA-ICOS risk tool for predicting cancer therapy–related cardiac dysfunction: a prospective cohort study

Anthracyclines and HER2-targeted breast cancer treatments can cause cancer therapy–related cardiac dysfunction (CTRCD). The Heart Failure Association–International Cardio-Oncology Society (HFA-ICOS) risk tool assesses this risk, but its accuracy remains uncertain. We aimed to (1) determine CTRCD incidence using the 2021 CTRCD definition in breast-cancer patients receiving doxorubicin and/or trastuzumab; (2) evaluate the HFA-ICOS risk proformas, and (3) assess the individual risk factors incorporated in the proformas. In this prospective study, 186 women with early-stage breast cancer were enrolled to undergo baseline and serial cardiac evaluations over 12 months. After exclusions, 177 patients were included for risk stratification using the Heart Failure Association–International Cardio-Oncology Society (HFA-ICOS) score. Baseline risk distribution was 67% low ( n = 116), 28% moderate ( n = 52), and 5% high ( n = 9). During follow-up, 53 patients (28.6%) developed cancer therapy–related cardiac dysfunction (CTRCD), corresponding to an overall incidence rate of 0.266 events per person-year (95% CI 0.200–0.348). Incidence rates were 0.326, 0.145, and 0.248 in the low-, moderate-, and high-risk groups, respectively; pairwise 365-day restricted mean survival time (RMST) comparisons did not remain statistically significant after Holm adjustment (all adjusted p > = 0.124). In Cox models adjusted for treatment type, CTRCD risk did not differ significantly between the moderate- and high-risk groups compared with the low-risk group. The ordinal HFA-ICOS category showed poor discrimination for time to CTRCD (Harrell C-index 0.43, 95% CI 0.37–0.49). The HFA-ICOS proforma showed limited ability to stratify CTRCD risk in this cohort. These findings highlight limitations in current guideline-based risk models and the need for improved stratification strategies.