NEW YORK — Heart disease is the leading cause of noncancer mortality in patients who survive an initial bout with Hodgkin's disease, an example of the importance of monitoring for heart disease in cancer survivors.
The relative risk for cardiovascular disease is about two- to sevenfold higher in Hodgkin's disease survivors compared with age- and gender-matched people with no cancer history, Dr. Ming Hui Chen said at a symposium on cardiovascular disease in cancer patients sponsored by the University of Texas M.D. Anderson Cancer Center.
Similar spikes in cardiovascular disease rates occur in survivors of other cancer types, a link that is mainly attributable to the chemo- or radiotherapy that cancer patients receive. The sequelae usually don't manifest until at least 15 years after cancer treatment. Surveillance for new-onset cardiovascular disease is challenging because the disease often presents atypically. Chest pain, for example, may be blunted in these patients because their chest nerves were damaged by radiation treatment and so are less sensitive, said Dr. Chen, associate director of the noninvasive cardiac imaging laboratory at the Brigham and Women's Hospital in Boston.
Dr. Chen and her associates have done cardiovascular disease follow-up studies on 182 patients in the Hodgkin's Disease Cardiac Study. The patients' median age at enrollment was 43, and at entry into the study they were an average of 15 years removed from their initial Hodgkin's disease treatments. A third of the patients received chemotherapy and the remainder had radiation therapy.
During about 4 years of follow-up, cardiovascular diseases were diagnosed in 12 patients (7%), including cases of coronary artery disease, complete heart block, drug-refractory atrial fibrillation, and valvular dysfunction. “For patients who are aged 40–50, the rate [of cardiovascular disease] is quite high,” Dr. Chen said at the meeting, also sponsored by the American College of Cardiology and the Society for Geriatric Cardiology.
Current estimates place more than 10 million cancer survivors in the United States, 60% of whom are adults, she said. Breast cancer survivors make up the largest subgroup, but there are also many who had childhood cancers. About 40% of childhood cancer survivors develop severe, disabling complications 30 or more years after their successful cancer treatments.
Guidelines for monitoring cardiovascular disease in childhood cancers survivors were published last February by the Cardiovascular Disease Task Force of the Children's Oncology Group (Pediatrics 2008;121:e387–96). Dr. Chen was a member of the task force.
The guidelines cited three cancer treatments that need regular screening later in life: treatment with an anthracycline, which can potentially cause cardiomyopathy, arrhythmias, or subclinical left-ventricular dysfunction; mediastinal radiation, which can lead to heart failure, cardiomyopathy, pericarditis, pericardial fibrosis, valvular disease, myocardial infarction, arrhythmia, or atherosclerotic heart disease; and neck radiation of 40 Gy or more, which can lead to carotid and subclavian artery disease.
Patients who undergo any of these treatments should be followed up with an annual history and physical, the guidelines said. In addition, patients who received an anthracycline or mediastinal radiation should receive a baseline echocardiography examination (or multiple gated-acquisition scan if treated with an anthracycline) followed by periodic follow-up echo examinations with the frequency dictated by the patient's age when treated and the cumulative dose received. These patients should also have a baseline electrocardiogram to evaluate their QT interval. Following mediastinal radiation, patients should also be screened with a fasting glucose and lipid profile every 3–5 years. Following neck radiation, patients should undergo Doppler ultrasound examinations of their carotid and subclavian arteries as clinically needed.