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    Study shows childhood cancer survivors exercise less

    Kirsten K. Ness, PT, PhD

    In a new study of adults who survived cancer as children, St. Jude researchers have found that many survivors lead sedentary lifestyles and are more likely to be less physically active than their siblings. The study’s results appear in the May issue of the journal Cancer.

    Childhood cancer survivors are at greater risk of obesity, diabetes and heart disease than the rest of the population. Cancer treatments such as cranial radiation can damage the hypothalamus and pituitary; the result is an abnormal metabolism, which increases the risk of obesity and diabetes. Also, chemotherapy with the drug anthracycline increases the risk of heart disease; and radiation to the body can cause blood vessels to become less pliant.

    “Physical activity is a key step that survivors can take to reduce the health risk of these effects,” said Kiri Ness, PhD, Epidemiology and Cancer Control, the study’s first author. “Medical center programs to encourage physical activity in adult survivors could help significantly. However, one problem is that researchers have not firmly established the factors that affect cancer survivors’ participation in physical activity.”

    To understand those factors, Ness and her colleagues drew on data from the Childhood Cancer Survivor Study (CCSS), a St. Jude-led consortium of 26 centers in the United States and Canada. The study gathers extensive data from the participating centers on more than 20,000 childhood cancer survivors who received diagnoses between 1970 and 1986.

    The researchers analyzed 9,301 CCSS participants’ answers to questions about their physical activity; as a comparison, the scientists also analyzed the same answers given by 2,886 siblings. The investigators compared those answers with information on physical activity obtained from a massive health survey database maintained by the Centers for Disease Control and Prevention.

    Because of the cohort’s large size, the researchers explored the relationships between health and exercise in all the different types of cancer. Also, because the cohort is older, Ness and her colleagues were able to investigate adult behaviors and relate them back to the data on their childhood cancers.

    “Thus, we could identify who has the highest risk of having an inactive lifestyle,” Ness said. “Knowing this makes it possible to begin to design interventions that will address the problems that put them at most risk.”

    The researchers found that the cancer survivors showed significant deficits in physical activity compared to their siblings. Survivors were less likely than their siblings to meet physical activity guidelines and more likely to report inactive lifestyles.

    “It was particularly striking that 23 percent of the survivors reported that they were completely inactive over the previous month, compared with 14 percent of their siblings,” Ness said.

    The researchers’ analysis revealed that survivors of medulloblastoma and osteosarcoma reported the most inactive lifestyles. Also associated with inactivity were treatments with cranial radiation or amputation as well as other factors, including gender, race, age and education level. If survivors smoked, were underweight or obese or had suffered from depression, they were also prone to inactivity.

    Ness hopes the findings will spark more research on the role of fitness in cancer survivors’ quality of life, as well as the design of facilities and programs to encourage good fitness in survivors.

    “For instance, if we know that patients with medulloblastoma who received cranial radiation are at a high risk for having inactive lifestyle as adults, we might design a rehabilitation program they can undergo while they are still children to encourage physical activity as they age,” Ness said.

    The investigators are launching follow-up studies to explore whether energy metabolism in cancer survivors affects their ability to benefit from exercise. Ness and her colleagues also plan to investigate whether programs to encourage exercise in both children and adult childhood cancer survivors can help them avoid heart disease, obesity and other health problems.

    Other authors of this paper are Sujuan Huang and Gregory Armstrong, MD, Epidemiology and Cancer Control; Leslie Robison, PhD, Epidemiology and Cancer Control chair; and Melissa Hudson, MD, Oncology.

    This research was funded by the National Cancer Institute and ALSAC.

    May 2009