New research suggests that fitness level may be associated with lower risk of some cancers and death.

Researchers at the University of Vermont found that men with a high fitness level in midlife appear to be at lower risk for lung and colorectal cancer, but not prostate cancer, and that higher fitness level also may put them at lower risk of death if they are diagnosed with cancer when they're older.

While the association between cardiorespiratory fitness (CRF) and cardiovascular disease (CVD) has been well-established, the value of CRF as a predictor of primary cancer has gotten less attention.

For the study, researchers looked at the association between midlife CRF and incident cancer and survival following a cancer diagnosis at the Medicare age of 65 or older. The study included 13,949 men who had a baseline fitness exam where CRF was assessed in a treadmill test. Fitness levels were assessed between 1971 and 2009 and lung, prostate and colorectal cancers were assessed using Medicare data from 1999 to 2009.

During an average 6.5 years of surveillance for the 13,949 men, 1,310 of them were diagnosed with prostate cancer, 200 with lung cancer and 181 men with colorectal cancer.

They found that high CRF in midlife was associated with a 55 percent lower risk of lung cancer and a 44 percent lower risk of colorectal cancer compared to men with low CRF. However this same association was not seen between midlife CRF and prostate cancer. The exact reasons for this are unknown, but researchers speculate men with high CRF may be more prone to undergo preventive screenings and therefore have a greater opportunity to be diagnosed with prostate cancer.

The study also found that high CRF in midlife was associated with a 32 percent lower risk for cancer death among men who developed lung, colorectal or prostate cancer at Medicare age compared with men with low CRF. And, high CRF in midlife was associated with a 68 percent reduction in CVD death compared with low CRF among men who developed cancer.

"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. These findings provide further support for the effectiveness of CRF assessment in preventive health care settings. Future studies are required to determine the absolute level of CRF necessary to prevent site-specific cancer as well as evaluating the long-term effect of cancer diagnosis and mortality in women," the study concludes.

The findings are detailed in JAMA Oncology.