Coronary Artery Dose-Volume Parameters Predict Risk of Calcification After Radiation Therapy

摘要

BACKGROUND Radiation exposure increases the risk of coronary artery disease (CAD). We explored the association of CAD with coronary artery dose-volume parameters in patients treated with 3D-planned radiation therapy (RT). METHODS Patients who received thoracic RT and were evaluated by cardiac computed tomography ≥ 1 year later were included. Demographic data and cardiac risk factors were retrospectively collected. Dosimetric data (mean heart dose, dsubmax/sub, dsubmean/sub, Vsub50/sub - Vsub5/sub) were collected for the whole heart and for each coronary artery. A coronary artery calcium (CAC) Agatston score was calculated on a per-coronary basis and as a total score. Multivariable generalized linear mixed models were generated. The predicted probabilities were used for receiver operating characteristic analyses. RESULTS Twenty patients with a median age of 53 years at the time of RT were included. Nine patients (45%) had ≥ 3/6 conventional cardiac risk factors. Patients received RT for breast cancer (10, 50%), lung cancer (6, 30%), or lymphoma/myeloma (4, 20%) with a median dose of 60 Gy. CAC scans were performed a median of 32 months after RT. CAC score was significantly associated with radiation dose and presence of diabetes. In a multivariable model adjusted for diabetes, segmental coronary artery dosimetric parameters (dsubmax/sub, dsubmean/sub, Vsub50/sub, Vsub40/sub Vsub30/sub, Vsub20/sub, Vsub10/sub, and Vsub5/sub) were significantly associated with CAC score 0. Vsub50/sub had the highest area under the ROC curve (0.89, 95% confidence interval, 0.80-0.97). CONCLUSIONS Coronary artery radiation exposure is strongly correlated with subsequent segmental CAC score. Coronary calcification may occur soon after RT and in individuals with conventional cardiac risk factors.