For childhood cancer survivors, hypertension dramatically exacerbates the likelihood of developing serious heart problems as adults, according to a study.
The Childhood Cancer Survivor Study, led by researchers with St. Jude Childrens Research Hospital in Memphis, is described as one of the first to focus on how hypertension, diabetes, obesity and elevated blood lipids contribute to cardiovascular disease in childhood cancer survivors.
The research, published in the Oct. 10 issue of the Journal of Clinical Oncology, concentrated on risk factors that often can be modified with diet, exercise and other lifestyle changes. The federally funded CCSS follows survivors of childhood cancer treated at 26 medical centers in the U.S. and Canada, with St. Jude as the coordinating center.
Based on the study data, the increased risk was greatest for survivors whose cancer treatment had included therapies associated with heart damage. The findings suggest risk factors linked to lifestyle, particularly hypertension, intensify the impact of those childhood cancer treatments and accelerate development of heart disease.
The findings raise hope that prevention or treatment of such risk factors might help reduce heart-related death and disability among the nations growing population of childhood cancer survivors, according to the study authors. For survivors, treatment-related heart disease is a leading cause of non-cancer death and disability.
The results reinforce the importance of annual medical screenings to check survivors blood pressure, weight, cholesterol and other health indicators, said Greg Armstrong, MD, the studys first and corresponding author and an associate member of the St. Jude Department of Epidemiology and Cancer Control. Screenings have a track record of reducing heart disease in the general population and are recommended for childhood cancer survivors.
Nationwide, there are an estimated 395,000 survivors of childhood cancer. With overall pediatric cancer survival rates at 80%, the number of survivors will continue to grow, the researchers noted.
Study methodology and results
The study included 10,724 childhood cancer survivors, half younger than 34, and 3,159 siblings whose average age was 36 and who had not been diagnosed with childhood cancer. The survivors were all at least five years from their cancer diagnosis and half had survived for more than 25 years.
Although similar percentages of survivors and siblings reported at least two preventable risk factors, by age 45 survivors were far more likely than the siblings to report severe, life-threatening or fatal heart problems. For example, 5.3% of survivors, compared with 0.9% of siblings, reported a diagnosis of coronary artery disease, and 4.8% of survivors compared with 0.3% of siblings reported suffering from heart failure.
The difference was even more dramatic when investigators focused on survivors whose cancer treatment included either chest irradiation or the anthracycline class of chemotherapy drug. Both are associated with an increased risk of serious heart problems. Although treatments have changed since survivors in this study battled cancer in the 1970s and mid-1980s, anthracyclines and chest irradiation still play essential roles in childhood cancer treatments, the researchers noted.
Such treatment-related risk left survivors with normal blood pressure at a five-fold increased risk of coronary artery disease. The researchers found survivors with the same treatment history but who also had developed hypertension were at a 37-fold increased risk. The researchers found similarly dramatic differences in the likelihood of heart failure, heart valve disease or arrhythmia depending on whether the at-risk survivors reported treatable risk factors in addition to their cancer treatment-related risk.
For survivors whose cancer treatment included cardio-toxic therapy, we found that preventable factors, particularly hypertension, resulted in a risk beyond what is likely from a simple additive effect, Armstrong said in a news release.
Study abstract: http://jco.ascopubs.org/content/31/29/3673.abstract