Partaking in cardiorespiratory fitness in youth may be associated with up to a 40% lower risk of developing nine cancer types later in life, according to a recent study published by Onerup et al in the British Journal of Sports Medicine.
Background
Cardiorespiratory fitness—including sustained periods of aerobic exercises such as running, cycling, swimming, and climbing stairs—is known to be associated with lower risks of certain cancer types. However, few large-scale, long-term studies of multiple cancer sites have been reported.
Study Methods and Results
In the new study, investigators used Swedish registries to analyze the background information, medical diagnosis, and mortality data of 1.2 million individuals who conscripted into the military service from 1968 and 2005 between the ages of 16 and 25 years.
At the start of their service, the individuals underwent a standard series of assessments including height, body mass index, blood pressure, muscular strength, and cardiorespiratory fitness. The investigators found that 365,874 of the individuals had a lower level of cardiorespiratory fitness, 519,652 of them had a moderate level of fitness, and 340,952 of them had a higher level of fitness.
The final analysis included 1.08 million individuals—84,117 of whom subsequently developed colorectal cancer, pancreatic cancer, bowel cancer, head and neck cancer, renal cell carcinoma, gastric cancer, esophageal carcinoma, hepatic cancer, and lung cancer during an average monitoring period of 33 years.
The investigators noted that the individuals with lower levels of cardiorespiratory fitness were more likely to be obese, have a history of alcohol and substance misuse, and have parents with lower educational attainment than individuals with higher levels of cardiorespiratory fitness. Further, compared with those who had lower levels of fitness at conscription, individuals with higher levels of cardiorespiratory fitness at conscription had a 5% lower risk of colorectal cancer (n = 2,337), a 12% lower risk of pancreatic cancer (n = 1,280), an 18% lower risk of bowel cancer (n = 3,222), a 19% lower risk of head and neck cancer (n = 2,738), a 20% lower risk of renal cell carcinoma (n = 1,753), a 21% lower risk of gastric cancer (n = 902), a 39% lower risk of esophageal carcinoma (n = 689), a 40% lower risk of hepatic cancer (n = 1,111), and a 42% lower risk of lung cancer (n = 1,635).
However, higher cardiorespiratory fitness was also associated with a 7% heightened risk of prostate cancer (n = 14, 232) and a 31% heightened risk of skin cancer (n = 23,064). The investigators suggested that prostate cancer screenings and exposure to sunlight may have accounted for the increased incidence of these cancer types.
Conclusions
The investigators stressed that because of the observational nature of their study, no firm conclusions can be drawn about cause and effect. They noted that they also didn’t have full data on other potential lifestyle risk factors such as diet, alcohol intake, and smoking; nor were they able to track any changes in cardiorespiratory fitness over time or gather any genetic information on the patients who participated in the study. Nevertheless, the investigators highlighted the fact that their findings are currently reflected in the ASCO guidelines on exercise during cancer treatment.
“This study shows that higher fitness in healthy young [individuals] is associated with a lower hazard of developing [nine] site-specific cancer [types], with the most clinically relevant hazard rates in the gastrointestinal tract,” underscored the study authors. “These results could be used in public health policymaking, further strengthening the incentive for promoting interventions aimed at increasing [cardiorespiratory fitness] in youth,” they concluded.
Disclosure: The research in this study was funded by the Swedish government, Assar Gabrielsson’s Foundation, the Swedish Research Council, and the Heart and Lung Foundation. For full disclosures of the study authors, visit bjsm.bmj.com.
