Three-Point Correction Factor Improves Accuracy of Framingham Risk Score in Breast Cancer Survivors

After surviving breast cancer (BC), women are at two- to sixfold greater risk of death due to cardiovascular disease (CVD) than women without BC. The Framingham Risk Score (FRS) is an estimate of an individual's risk of CVD but does not account for cancer history. The objective of this study was to determine whether BC history modified FRS prediction of CVD events and if a derived correction factor would improve its accuracy.

Women from the UK Biobank prospective cohort with and without (controls) a history of BC were included and those who experienced a CVD event before study enrollment were excluded. The primary outcome was a composite of CVD events derived from primary care/hospital visits and death with CVD International Classification of Diseases 10th Revision codes during 10 years of follow-up.

BC survivors (n = 4808) and 171,427 controls were included. BC survivors had > 50% higher risk of CVD events (adjusted hazard ratio [aHR], 1.51; 95% confidence interval [CI], 1.39-1.65). FRS (%) was a significant predictor of CVD in both groups with attenuation in BC survivors (aHR, 1.03 [95% CI, 1.02-1.05] vs aHR, 1.06 [95% CI, 1.06-1.07]). A greater proportion of BC patients experienced CVD events within the low (aHR, 1.65 [95% CI, 1.44-1.99]) and intermediate (aHR, 1.36 [95% CI, 1.19-1.54]) FRS categories. A 3-point derived correction factor for BC history added to the FRS sum increased the predictive accuracy for BC survivors (observed/expected improved from 1.41 to 0.93).

FRS significantly underestimated CVD events among BC survivors, but +3-point correction factor substantially improved predictive ability. This is a simple strategy that can be used by clinicians to improve CVD risk management among BC survivors.