Fitness should be assessed by doctors to so that men can better understand their risks of developing cancer later in life, the researchers found.
The study followed almost 14,000 men with an average age of 49 for an average of 6.5 years.
Those whose medical tests, cardiovascular risk factors and treadmill exercises showed them to be fit were less likely to develop lung and colon cancer after the age of 65.
No such link was found with prostate cancer, which the researchers suspect is due to increased awareness and better screening.
Better fitness meant that those who did develop cancer were 32% less likely to die as a result, according to the research, published in Jama Oncology.
Physical activity is known to reduce the risk of heart disease and cancer but the researchers say that fitness levels have not been used to predict the risk of specific cancers before.
‘To our knowledge, this is the first study to demonstrate that CRF is predictive of site-specific cancer incidence, as well as risk of death from cancer or CVD following a cancer diagnosis,’ the researchers, from the University of Vermont, wrote.
‘These findings provide further support for the effectiveness of CRF assessment in preventive health care settings.’
Tom Stansfeld from Cancer Research UK said: ‘Investigating links between men's fitness levels and cancer risk, rather than just the amount of physical activity they do, is a new approach.
‘In women, other research has shown that getting moving can reduce the risk of breast and womb cancers as well.
‘Interestingly, the study also found a positive effect of fitness on reducing lung cancer risk, but more research is needed to understand this potential link better.'