Development and Validation of a Risk Score Model for Predicting the Cardiovascular Outcomes After Breast Cancer Therapy: The CHEMO‐RADIAT Score

BACKGROUND: Cardiovascular disease is an important cause of mortality among survivors of breast cancer (BC). We developed a prediction model for major adverse cardiovascular events after BC therapy, which is based on conventional and BC treatment‐related cardiovascular risk factors. METHODS AND RESULTS: The cohort of the study consisted of 1256 Asian female patients with BC from 4 medical centers in Korea and was randomized in a 1:1 ratio into the derivation and validation cohorts. The outcome measures comprised cardiovascular mortality, myocardial infarction, congestive heart failure, and transient ischemic attack/stroke. To correct overfitting, a penalized Cox proportional hazards regression was performed with a cross‐validation approach. Number of cardiovascular diseases (myocardial infarction, peripheral artery disease, heart failure, and transient ischemic attack/stroke), number of baseline cardiovascular risk factors (hypertension, age ≥60, body mass index ≥30 kg/m(2), estimated glomerular filtration rate <60 mL/min per 1.73 m(2), dyslipidemia, and diabetes mellitus), radiation to the left breast, and anthracycline dose per 100 mg/m(2) were included in the risk prediction model. The time‐dependent C‐indices at 3 and 7 years after BC diagnosis were 0.876 and 0.842, respectively, in the validation cohort. CONCLUSIONS: A prediction score model, including BC treatment‐related risk factors and conventional risk factors, was developed and validated to predict major adverse cardiovascular events in patients with BC. The CHEMO‐RADIAT (congestive heart failure, hypertension, elderly, myocardial infarction/peripheral artery occlusive disease, obesity, renal failure, abnormal lipid profile, diabetes mellitus, irradiation of the left breast, anthracycline dose, and transient ischemic attack/stroke) score may provide overall cardiovascular risk stratification in survivors of BC and can assist physicians in multidisciplinary decision‐making regarding the BC treatment.