Is the coronary artery calcium score associated with acute coronary events in breast cancer patients treated with radiotherapy?

BACKGROUND AND PURPOSE: The main objective of this study was to test whether pre-treatment coronary artery calcium (CAC) was associated with the cumulative incidence of acute coronary events (ACE) among breast cancer (BC) patients treated with postoperative radiotherapy (RT).

MATERIAL AND METHODS: The study population consisted of 939 consecutive female BC patients treated with RT. The association between CAC and ACE was tested using Cox-proportional hazard models. Known risk factors for ACE and the mean heart dose (MHD), collected from three-dimensional computed tomography planning data, were tested for confounding.

RESULTS: CAC scores varied from 0 to 2,859 (mean 27.3). The 9-year cumulative incidence of ACE was 3.2%, this was significantly associated with the pre-treatment CAC score. After correction for confounders, age, history of ischemic heart disease, diabetes, Body Mass Index ≥30, MHD, hypercholesterolemia and hypertension, the hazard ratio for ACE for the low and the combined intermediate and high CAC score category were 1.42 (95%CI: 0.49-4.17; p = 0.519) and 4.95 (95%CI: 1.69-14.53; p = 0.004) respectively, compared to the CAC zero category.

CONCLUSIONS: High pre-treatment CAC is associated with ACE in BC patients treated with postoperative RT, even after correction for confounding factors such as MHD.