Cardiovascular Disease in Select Cancer Subgroups
Hodgkin lymphoma (HL) continues to be the pediatric malignancy associated with the greatest risk of cardiovascular disease, with a 13.1 excess absolute risk per 10,000 person years for cardiovascular death. Newer treatment approaches are specifically designed to reduce exposure to cardiotoxic agents (e.g., total anthracycline dose) and radiation dose and volume. Moreover, newer trials explore the safe elimination of radiation from primary therapy.
Data from the German-Austrian DAL-HD studies show a dose response for cardiac diseases in children treated for HL with combined radiation and anthracycline-based chemotherapy (cumulative doxorubicin dose was uniformly 160 mg/m2). The 25-year cumulative incidence of cardiac diseases was 3% with no radiation therapy, 5% after 20 Gy, 6% after 25 Gy, 10% after 30 Gy, and 21% after 36 Gy. An older study of 635 patients treated for childhood HL confirms the risks that occur after higher-dose radiation therapy. The actuarial risk of pericarditis requiring pericardiectomy was 4% at 17 years posttreatment (occurring only in children treated with higher radiation doses). Only 12 patients died of cardiac disease, including seven deaths from acute MI; however, these deaths occurred only in children treated with 42 Gy to 45 Gy. In an analysis of 48 asymptomatic patients treated for HL from 1970 to 1991 with mediastinal therapy (median dose 40 Gy) and screened for the presence of subclinical cardiac abnormalities, 43% had unsuspected valvular abnormalities, 75% had a conduction abnormality or arrhythmia, and 30% had reduced VO2 during exercise tests. These abnormalities were noted at a mean of 15.5 years posttherapy suggesting that survivors of HL treated with high doses of mediastinal radiation therapy require long-term cardiology follow-up. Among children treated with 15 Gy to 26 Gy, none developed radiation-associated cardiac problems.
The risk of delayed valvular abnormalities and CAD after lower radiation doses requires additional study of patients followed for longer periods of time to definitively ascertain lifetime risk. Nontherapeutic risk factors for CAD—such as family history, obesity, hypertension, smoking, diabetes, and hypercholesterolemia—are likely to impact the frequency of disease.[7,8,60]