The Contribution of Thoracic Radiation Dose Volumes to Subsequent Development of Cardiovascular Disease in Cancer Survivors.

Background: Although radiation therapy (RT) has been recognized for contributing to cardiovascular disease (CVD), it is unknown whether specific doses received by cardiovascular tissues influence development.

Objective: In this pilot study, we examined the contribution of RT dose distribution on the development of CVD events in patients with cancer within 5 years of RT.

Methods: A retrospective case-controlled design was used matching 28 cases receiving thoracic RT who subsequently developed an adverse CVD event with 28 controls based upon age, gender, and cancer type. Dose volume histograms of nongated computed tomography scans received during RT characterized the dose delivered to the heart. Heart chambers were segmented using an atlas approach, and radiomics features for the segmentation as well as planning dose in each chamber were tabulated for analysis.

Result: No significant differences were observed in the RT dose statistics between groups, preexisting CVD, nor significant differences of RT doses delivered to distinct chambers of the heart. Cases were found to have greater CVD risk factors at the time of cancer diagnosis. Morphological significant differences for perimeter on border ( P = .043), equivalent spherical radius ( P = .050), and elongation ( P = .038) were observed, with preexisting CVD having the highest values (ie, larger hearts).

Conclusion: Traditional CVD risk factors were more prevalent in the cases who developed CVD. No differences were observed in doses of RT. Of note, we observed significant differences in heart morphology and mass in known diseased hearts on the pretreatment scans. These new metrics may have implications for the measurement and quantification of CVD.