Over the last several decades, improved diagnosis and treatment have led to more and more long-term survivors of childhood cancer. Yet the bad news is that these life-saving treatments can also play a role in health challenges years after the treatment has ended. Adult survivors of childhood cancers, overall, face increased risk of heart disease, obesity, and other cancers. In general, these adults have an increased risk of an earlier mortality than the general population.
Now comes a study suggesting that vigorous exercise may help lengthen survival among this group of survivors. The study, published in JAMA Oncology, indicates that running and other bouts of regular vigorous exercise as young adults, improves the survival of adults who were diagnosed with cancer as children.
The study shows an association between exercise and improved survival but cannot prove that exercise causes the observed decrease in mortality directly. Yet it builds on the clear research among the general population showing that physical activity helps people live longer and healthier lives. AICR's latest analysis of the global evidence found that physical activity lowers risk of breast, endometrial, and colon cancers. Research shows that being physically active also lowers risk for heart disease and diabetes, to name just a few of its benefits.
In this recent study, researchers analyzed data from approximately 15,000 adults who were part of the Childhood Cancer Survivor Study. All study subjects had been diagnosed with cancer before they turned 21. They reported on their lifestyle habits when they enrolled in the study and periodically through the years, by answering a single, reliability-validated, question on vigorous exercise.
Government guidelines recommend 75 minutes each week of vigorous-intensity or 150 minutes each week of moderate-intensity aerobic physical activity (such as brisk walking or tennis) – or a combination of moderate-to-vigorous. Exercise experts measure activity in metabolic equivalents, or METs.
Reported amounts of physical activity were converted into the standardized metabolic equivalent tasks (METs) per week, the amount of energy expended per week through activity.
After 15 years follow-up, those who reported being vigorously active for at least 20 minutes a week (3 MET-hour/week of vigorous exercise) had lower risk of mortality, relapse, and health-related mortality compared to those active fewer than 20 minutes.
This was after adjusting for recognized risk factors, such as chronic health conditions, smoking, and treatment. Those who were vigorously active for 60 to less than 80 minutes per week (9 to 12 MET hours/week), for example, had close to a 7 percent risk of mortality during the course of the study compared to an almost 12 percent risk for those active less than 20 minutes per week. The authors derived an optimal level of vigorous exercise of 15-18 MET hours/week (2.5 – 3 hours per week).
The authors also examined how peoples’ levels of vigorous activity changed over time. Survivors who reported increasing the amount they exercised were more likely to be non-smokers and had fewer chronic health conditions, although the study took these factors into account in its analyses.
The study has several caveats, including that its analyses were limited to survivors who were alive for all the follow-up questionnaires raising the potential of survival bias. Also, exercise was assessed by a self-report single question, albeit validated for reliability.
However, the findings corroborate those in the general population, the authors write, and may be of importance for the large and rapidly growing global population of adult survivors of childhood cancer who are at substantially higher risk of mortality.
AICR recommends that cancer survivors follow the general recommendations for cancer prevention if able (and unless otherwise advised), for physical activity along with diet and weight maintenance. That means following government guidelines to include physical activity as part of everyday life and avoid inactivity.
The JAMA Oncology study was supported by the National Cancer Institute; the Cancer Center Support, and the American Lebanese-Syrian Associated Charities. Authors are supported by grants from the National Cancer Institute. AKTIV Against Cancer, and the Kavli Trust.
Published on July 25, 2018