Childhood Leukemia survivors at higher risk for obesity
Overcoming pediatric cancer may only mark the beginning of a young survivor's lifelong battle to stay healthy. While survivors of childhood acute lymphoblastic leukemia (ALL) face an increased risk of developing serious health complications as a result of their cancer treatment, for a variety of reasons many avoid simple exercise and healthy lifestyle changes that could reverse the damage, according to a team of researchers based at Memorial Sloan-Kettering Cancer Center.
Adult survivors of childhood ALL are less physically active than the general U.S. population, the team reports in the July issue of Cancer Epidemiology, Biomarkers, & Prevention, a journal of the American Association for Cancer Research. Furthermore, adult survivors of ALL who received cranial radiotherapy (CRT), or "whole brain radiation," as children reported the lowest activity among all adults, suggesting that the type of therapy administered to a child may impair his or her physical activity in the future.
To protect adult childhood cancer survivors from a future of disease, researchers say patients should work with health care providers to develop plans for healthier and more active lifestyles.
"Research shows that physical activity can undo risk caused by treatment," said senior author Kevin C. Oeffinger, M.D., from Memorial Sloan-Kettering Cancer Center, New York, N.Y. "Small, incremental steps can make a big difference in improving health outcomes."
Dr. Oeffinger and his colleagues compared the physical activity levels of over 2,600 adult survivors of ALL, ages 18 to 44, as reported by patients in the Childhood Cancer Survivor Study (CCSS) in 2003, to physical activity of age-matched adults in the general U.S. population, as reported in the 2003 Behavioral Risk Factor Surveillance System (BRFSS) survey. The CCSS is a multi-institution study sponsored by the National Cancer Institutes, and the BRFSS is a state-based survey conducted by the Centers for Disease Control (CDC). In both surveys, study participants were asked to report the number of times they had participated in physical activity or exercise during the prior month.
The study found that adult ALL survivors were less likely to meet the CDC physical activity guidelines (52.8 percent vs. 48.2 percent) and more likely to report no moderate or vigorous physical activity during the month preceding the survey (23 percent vs. 20.3 percent), with the highest levels of physical inactivity in ALL survivors who had received CRT treatment. Women who were treated with a moderate dose of CRT were twice as likely to be physically inactive as women in the general population.
"It's important to remember that these patients are not couch potatoes or lazy," said Dr. Oeffinger. "Our findings suggest that CRT has fundamentally altered something in the central nervous system that's leading to a decrease in levels of physical activity."
Because exercise reduces the risk of developing cardiovascular diseases, the CDC advises Americans to engage in a minimum of 30 minutes of moderate physical activities such as brisk walking, gardening, or vacuuming five days per week, or vigorous physical activities such as running, aerobics, or heavy yard work three days per week. While more than half of the U.S. population fails to meet CDC recommendations, low physical activity among adult survivors of ALL may further increase this group's already high risk for obesity, cardiovascular disease and mortality, researchers said.
Though the addition of CRT to ALL therapy over 40 years ago led to a marked increase in survival rates, research has since linked CRT to reduced cognitive function, hormonal imbalance and obesity. In some patients, CRT may cause loss of postural and motor control, balance, and/or muscle weakness, which may lead to decreased physical activity.
Because of the risks associated with CRT and the availability of improved chemotherapy drugs to treat ALL, CRT is now only used to treat children with particularly aggressive forms of ALL. According to Dr. Oeffinger, approximately 10 to 15 percent of ALL patients today are treated with CRT.
Although childhood cancer patients are less likely to receive CRT than they were 20 years ago, Dr. Oeffinger says modern chemotherapy for ALL may also lead to decreased levels of physical activity, and needs further study. To reduce the long-term negative effects of chemotherapy on childhood cancer survivors, researchers hope to teach children and their families healthy lifestyle habits early, so they can carry them into adulthood.
"The storyline is that physical inactivity and obesity outcomes are based upon type of therapy administered to patient," said Dr. Oeffinger. "Importantly, there are things we can do to intervene and to help childhood cancer survivors to regain active lifestyles that will protect the patient in the long run."
This research was funded by the Department of Health and Human Services, the Children's Cancer Research Fund, the American Lebanese Syrian Associated Charities, and the University of Rochester School of Medicine.
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