Out of approximately 10 million cancer survivors in the United States, an estimated 270,000 were diagnosed when they were under the age of 21. With advances in treatment and screening, almost 80 percent of children now diagnosed with cancer survive at least five years after diagnosis. Many will be cured.
But survivors of childhood cancer are at increased risk for secondary cancers, as well as osteoporosis, cardiovascular disease, diabetes and other health disorders. In recent years, the growing population of childhood cancer survivors has spurred research in the area of diet and physical activity on survivors’ health and quality of life.
Maintaining a healthy weight, healthy diet and regular exercise is essential to prevent cancer and other chronic health conditions for everyone, but these lifestyle factors become even more critical for childhood cancer survivors because of what they were exposed to as children, said Cheryl Cox, RN, PhD, an Associate Member at St. Jude Children’s Research Hospital, who has played a major role in analyzing data from the largest childhood cancer survivor study in North America.
"Everything that’s true with the general population in terms of being healthy that’s magnified here in terms of need and urgency," said Cox. For example, obesity among childhood cancer survivors who have had exposure to toxic drugs is potentially more threatening than for the obese that have not had these exposures. "We’ve been so focused on cure and we’ve done a fantastic job that we have previously not focused as much on treatment-related late effects or health promotion for the child."
Some of the strongest data about childhood cancer survivors stem from the Childhood Cancer Survivor Study (CCSS), a St. Jude-led consortium of centers in the U.S. and Canada. Initiated in 1994, this study is tracking approximately 20,000 individuals who survived five or more years after diagnosis. Roughly 4,000 of the survivors’ siblings serve as the comparison group.
An analysis drawn from the CCSS found that almost two-thirds of adult survivors experience at least one chronic health condition. Over a quarter of the survivors had a severe or life-threatening condition, and incidence appeared to increase over time. For cancer, a study published last year found that overall recurrence for the most common pediatric cancers was 4.4 percent at 10 years and 6.2 percent at 20 years.
Although obesity, unhealthful diets and inactivity can compound these chronic health conditions, studies consistently show that childhood cancer survivors do not engage in healthy behaviors, says Melinda Stolley, PhD, an Assistant Professor of Medicine at the University of Illinois at Chicago. Stolley recently conducted a review of all published studies around diet, physical activity and related interventions among childhood cancer survivors.
Overall, the review found that few childhood cancer survivors eat nutritious diets and many are not regularly physically active. Alcohol use, smoking and overweight mirror that of the general population. The relatively few studies on childhood survivors are consistent with those on adults, which show many cancer survivors tend to make few lasting changes in eating or activity habits. "Survivors have a tendency to say they’re cured and not think about it again," said Cox
Along with chronic diseases, childhood cancer survivors face issues relating to quality of life, depression and fatigue, which physical activity may influence. In one study published last year, for example, researchers found that leisure time physical activity was modestly but significantly linked with improved health related quality of life. The study surveyed 215 adolescent and adult childhood cancer survivors. For adolescents, higher amounts of physical activity were linked with an improved overall health-related quality of life and improved cognitive and social functions. For adults, physical activity was linked with improving the activities of daily living, such as walking and climbing stairs.
"Kids who were more active before they were diagnosed were more likely to experience these benefits, even after adjusting for cancer diagnosis," said Raheem J. Paxton, a Postdoctoral Fellow at University of Texas M. D. Anderson Cancer Center and lead author of the study. "Activity is essential for this population."
Activity during treatment may also help childhood cancer patients minimize irreversible damage, says Cox. In the first study of its kind, Cox and her colleagues have recently begun a five-year trial that starts a highly structured physical activity intervention seven to ten days after a child with leukemia begins chemotherapy. Previously, said Cox, during treatment "we would notice these children had limited mobility in their joints, fatigue, and their physical function was way, way below normal." It was only after therapy (2.5 years) that the child would then start exercising. "The hope is that we will maintain or increase bone mineral density and content, and preserve physical function in these children."
Intervention research among childhood cancer survivors is extremely limited, but experts note the importance of working with the child’s parent or guardian to improve health behaviors.
In a survey of childhood cancer survivors by Wendy Demark-Wahnefried, PhD, RD, a Professor of Behavioral Science at MD Anderson Cancer Center, responders said they would want someone to participate with them in a healthy behavior intervention and the partner they preferred most often was their mother. "That’s something we should pay attention to."
A 2005 survey by Demark-Wahnefried found, surprisingly she says, that childhood cancer survivors preferred mailed interventions instead of computer-based, telephone or in-person. Yet her later study with a different population found more receptivity to computer-based interventions. Survivors are all different and interventions will vary: "It’s not going to be a one-size fits all."
Because research primarily focuses on non-Hispanic white participants, Stolley is currently conducting a study on health-promoting behaviors among minority childhood cancer survivors in order to design interventions. Along with physical activity and dietary behaviors, the study will examine how socio-cultural factors such as ethnic identity, spirituality and social support are linked with health risks and behaviors.
But before interventions can even start, the first step is awareness. Experts say that primary care providers and other health practitioners are often unaware of the many risks and long-term care issues childhood cancer survivors face. The research is relatively new and physicians do not generally come across many in their practice.
"A discussion on health behaviors should be an integral part of an annual physical," says Stolley. We may not have specific data yet on cancer recurrence for childhood survivors but we can look at it for other diseases such as osteoporosis and cardiovascular disease. "We know enough to be advising follow a low-fat diet, eat fruits and vegetables, exercise regularly most days of the week, use sunscreen we know this will help."
from: ScienceNow No.31, Winter 2010All active news articles