Exercise is one of the top health-promoting behaviors an individual can adopt. It's known to lessen risk of heart problems, cognitive decline, some cancers, and mental health disorders, as well as all-cause mortality (death by any cause). And new research suggests those benefits are also true for survivors of childhood cancer survivors.
"Childhood cancer survivors remain at substantially elevated risk of mortality with life expectancy shortened, on average, by 10 years compared with the general population," noted Jessica Scott, PhD, Assistant Member in the Department of Medicine at Memorial Sloan Kettering Cancer Center, New York City, and a coauthor of the new research. "This is primarily due to treatment-related effects (such as, subsequent malignant neoplasms and cardiovascular disease, [among others]). Given this excess risk, we know that strategies that can offset treatment-related effects are of major clinical importance."
The study, published online ahead of print in JAMA Oncology, was a multicenter cohort analysis of 15,450 adults who had been diagnosed with cancer before age 21 from pediatric hospitals in the U.S. and Canada between 1970 and 1999 (2018; doi:10.1001/jamaoncol.2018.2254). The individuals were all part of the Childhood Cancer Survivor Study and were followed through 2013. The researchers looked at the association between weekly self-reported vigorous exercise and mortality (including overall death rates and cause-specific death rates).
The data showed in a median analysis after 10 years and in the full analysis after 15 years that the cumulative incidence of all-cause mortality was in fact higher for those with lower weekly vigorous exercise and lower for those who did more vigorous exercise on a weekly basis.
After 15 years, there was a significant inverse association between exercise and all-cause mortality such that, compared to those reporting no weekly vigorous exercise, those reporting approximately 1.5-2 hours per week of vigorous exercise had a 42 percent reduction in mortality, Scott said.
Another analysis of the data showed that after an 8-year period, those who increased weekly exercise by as little as 40 minutes per week saw a 40 percent reduction in all-cause mortality, compared to those who kept their exercise at about 30 minutes or less per week over that time.
The amount of exercise that conferred the most benefit to survivors of childhood cancer (in terms of reducing risk of all-cause mortality) was equivalent to about 1.5-2 hours of brisk walking per week. "However, benefits were observed even with approximately 40 minutes per week of vigorous exercise," Scott said, noting this data was observational, so randomized controlled trials would be needed to more accurately identify an ideal dose. Here's why Scott says this new data is so important.
1 What does this data tell us that we didn't already know about the late effects of childhood cancers and survivors' risks?
"In the general population, adherence to healthy lifestyle behaviors, including regular exercise, is associated with substantial reductions in cardiovascular disease mortality and mortality from any cause. Exercise also reduces the primary incidence of several forms of cancer and the risk of recurrence following a diagnosis of certain adult-onset cancers (like those of the breast, colon, and prostate).
"But whether these findings extended to adult survivors of childhood cancer with excess risk of mortality was not known. Accordingly, we wanted to evaluate the association between exercise in early adulthood and change in vigorous exercise on mortality in long-term adult survivors of childhood cancer participating in the Childhood Cancer Survivorship Study.
"This study was unique in that it included a large sample size (of more than 15,000 cancer survivors); it included a long-term duration of follow-up [including a median follow-up at approximately 10 years]; it focused on at least 5-year survivors of cancer; and [it investigated] change in exercise exposure (median interval of approximately 8 years)."
2 What types of interventions are needed to spread this message that survivors of childhood cancers need to be exercising?
"One common question by patients is 'what is the best exercise program for me?' This is one of the most important questions in exercise-oncology research and one that will likely require many years to answer. What we've found is that one size of exercise does not fit all. However, based on current evidence in oncology settings, as a first step, patients may need to check with a doctor before beginning an exercise program.
"Once cleared for activity, the exercise guidelines for cancer patients/survivors are to: 1) avoid inactivity; 2) if relatively new to exercise, perform either 150 minutes of moderate-intensity aerobic physical activity or 75 minutes of vigorous-intensity aerobic physical activity each week; and 3) if a regular exerciser, try increasing the moderate-intensity physical activity to 300 minutes or your vigorous-intensity physical activity to 150 minutes each week.
"These recommendations can be achieved by adding a few minutes of activity to a daily routine, such as taking the stairs, adding an extra 15-minute walk before/after work (or at lunch), or walking a little faster or changing a walking route from a flatter route to one with a few small hills. There are also cancer-experienced exercise specialists (clinical exercise physiologists, kinesiologists, and physiotherapists) and programs (such as LIVESTRONG at the YMCA) that can help to initiate a new exercise program following a cancer diagnosis. Small steps can make a big difference for cardiovascular health."
3 What is the takeaway message about this new work?
"There are currently approximately 16 million adult cancer survivors in the U.S., of which approximately 500,000 are adult survivors of childhood malignancies. These numbers are estimated to reach approximately 24 million [cancer survivors] and approximately 750,000 [adult survivors of childhood cancers], respectively, by the year 2030.
"Our findings support counseling all survivors, whenever appropriate, to increase participation in vigorous exercise for approximately 60 minutes a few days a week."