Exercise linked to reduced mortality in survivors of childhood cancer

1. In this retrospective cohort analysis, adult survivors of childhood cancer demonstrated reduced mortality with increasing levels of vigorous exercise in a week.

2. Increasing the degree of vigorous exercise was also linked to a reduction in mortality compared to maintaining activity levels.

Evidence Rating Level: 3 (Average)      

Study Rundown: Adult survivors of childhood cancer demonstrate significantly higher mortality compared to the general population, out of proportion to the rate of recurrence for their primary cancer. The increase in morality is likely multifactorial reflecting cancer and therapy-related factors as well as development of comorbid conditions and alterations in health-related behaviors. The current study sought to evaluate the effect of vigorous exercise on mortality in adult survivors of cancer. The study found that increasing levels of activity were associated with reductions in all-cause mortality. Increasing rather than maintaining low activity levels was also linked to reduced mortality.

The study provides insight into one of the factors that affect long-term survival in pediatric cancer survivors. While physical activity is important for mortality in the general population, it may be more important for this population with an increased baseline mortality as it is one of the few modifiable factors affecting their survival. The study has numerous strengths including the longitudinal assessment and large cohort size. The main limitations of the study are the retrospective design allowing for bias, and the lack of delineation of which causes of death specifically that exercise may reduce.

Click to read the study in JAMA Oncology

Relevant Reading: Exercise Intervention in Pediatric Patients with Solid Tumors: The Physical Activity in Pediatric Cancer Trial.

In-Depth [retrospective cohort]: This study use data from the Childhood Cancer Survivorship Study (CCSS) which followed childhood cancer survivors longitudinally. Participants were included if they had a cancer diagnosis prior to age 21, received therapy, survived at least 5 years following diagnosis and were at least 18 years old at time of enrollment. Participants for whom death and cause of death information was not obtained were excluded, as were those who did not complete the exercise question on the survey. Vigorous exercise level was based on the answers to the following question: “on how many of the past 7 days did you exercise or do sports for at least 20 minutes that made you sweat or breathe hard (eg, jogging, basketball, etc)?”.

For the 15 450 survivors included in the cohort, median age at enrollment was 25.9 years and median follow up was 9.6 years. The degree of exercise demonstrated an inverse relationship with mortality after adjusting for chronic health conditions and treatment exposures (p = 0.2), with those exercising 15-18 MET-h/week having a mortality of 5.7% compared to 11.7% in those who did no exercise. Increasing ones exercise was linked to a reduced mortality compared to maintaining low levels of exercise (RR 0.60; 95%CI, 0.44-0.82; p = 0.001).

Image: PD

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