High cardiorespiratory fitness may protect against 9 types of cancer in men

Good cardiorespiratory fitness in youth is associated with up to a 40% lower risk of developing 9 specific cancers later-; at least in men-; offers a large long-term study published online in British Journal of Sports Medicine.

These include cancers of the head and neck, esophagus (gullet), stomach, pancreas, liver, bowel, kidney and lung.

Cardiorespiratory fitness refers to a person’s ability to do aerobic exercise such as running, cycling and swimming for extended periods or even climbing stairs. It is known to be associated with lower risks of some cancers, but few large, long-term studies at multiple cancer sites have been reported.

The researchers therefore used linked data from the Swedish register up to the end of 2019, covering background information, medical diagnoses and deaths for conscripts who started their military service between 1968 and 2005.

At the start of their service, when they were between the ages of 16 and 25, conscripts were put through a standard battery of assessments. These include height, weight (BMI), blood pressure, muscle strength and cardiorespiratory fitness.

Recruits with a low level of cardiorespiratory fitness were slightly more likely to be obese, more likely to have a history of alcohol and substance abuse, and to have parents with less education than recruits with a higher level of fitness.

A total of 365,874 recruits had a low level of cardiorespiratory fitness; 519,652 had a moderate level; and 340,952 are high level.

The final analysis included more than 1 million men (1,078,000), 84,117 (7%) of whom subsequently developed cancer at at least one site during a median follow-up of 33 years.

Compared to men with low levels of fitness at enlistment, higher cardiorespiratory fitness was linearly associated with lower risk of developing specific cancers.

Associated with 5% lower risk of rectal cancer (2337); 12% lower risk of pancreatic cancer (1280); 18% lower risk of bowel cancer (3222); 19% lower risk of head and neck cancer (2,738 men); 20% lower risk of kidney cancer (1753); 21% lower risk of stomach cancer (902); 39% lower risk of esophageal cancer (689); 40% lower risk of liver cancer (1111); and a 42% lower risk of lung cancer (1635).

But higher cardiorespiratory fitness was also associated with a 7% increased risk of prostate cancer (14,232 men) and a 31% increased risk of skin cancer (23,064). Prostate cancer screening and exposure to sunlight may explain these findings, the researchers suggest.

This is an observational study, so no firm conclusions can be drawn about cause and effect, and the researchers acknowledge that they did not have complete data on other potentially influential lifestyle risk factors, such as diet, alcohol intake and smoking, on -specially. Nor were they able to track any changes in cardiorespiratory fitness over time or gather genetic information about the participants.

However, their findings are reflected in the American Society of Clinical Oncology’s guidelines on exercise during cancer treatment, they point out.

And they conclude: “This study shows that higher physical fitness in healthy young men is associated with a lower risk of developing 9 of 18 site-specific cancers examined, with the most clinically relevant hazard levels in gastric – the intestinal tract.

“These results can be used in the development of public health policies, further strengthening the incentive to promote interventions aimed at increasing [cardiorespiratory fitness] in youth.”