Intense aerobic exercise could help prevent cancers, such as pancreas, stomach and head and neck cancers.
Better cardiorespiratory fitness in young men lowers the risk of cancer at nine specific sites by up to 40%, according to a new Swedish study.
Good cardiorespiratory fitness is known to be linked to a decreased risk of many cancer types. According to the researchers, the results of this study demonstrated the first associations between higher cardiorespiratory fitness and lower risk of kidney, rectal, colon, liver, pancreas, stomach, oesophagus and head and neck cancers.
This population-based cohort study, published in the British Journal of Sports Medicine, assessed the risk of 18 site-specific cancers in over one million men aged 16-25 with cardiorespiratory fitness levels recorded at military conscription between 1968 and 2005. Those with a cancer diagnosis before or within five years of conscription and those who died or left Sweden within five years of conscription were excluded from the study.
Over the follow up period, which averaged 33 years, cancer was reported in the Swedish National Patient Register for 7% of the men included in the study. When compared to low fitness levels (a score of 1-5 on a standardised fitness scale of 1-9), higher cardiorespiratory fitness (score 8-9) was associated with lower risk of cancers in the rectum (5%), pancreas (12%), bowel (18%), head and neck (19%), kidney (20%), stomach (21%), oesophagus (39%), liver (40%) and lung (42%).
Conversely, high cardiovascular fitness was associated with increased risk of prostate (7%) and malignant skin (31%) cancers. Previous studies have suggested that the increased risk may be a result of increased screening and increased UV exposure respectively, the researchers wrote.
The protective effects of cardiorespiratory fitness were generally independent of BMI. But this was not the case for bladder cancer or Hodgkin’s lymphoma. Cardiorespiratory fitness was only protective against these two cancers in patients who were obese or overweight, suggesting that cardiorespiratory fitness may be even more vital in individuals of an unhealthily high weight.
The risk of developing CNS, thyroid and most haematological cancers was not affected by cardiorespiratory fitness.
The authors said the association between low cardiorespiratory fitness and risk of lung cancer was mostly explained by smoking status.
They suggested that the link between cardiorespiratory health and site-specific cancers may be explained by differences in physical activity.
“Our results may indicate that public health efforts aimed at reducing cancer should focus on aerobic physical activity of sufficient relative intensity to increase cardiorespiratory fitness,” the authors wrote.
The study was limited by a lack of information on other potential risk factors such as alcohol consumption and diet as well as fitness information over time.
