High levels of fitness in middle age can help men survive cancer, a study has found.

Keeping fit reduced the chances of those who developed lung, bowel or prostate cancer dying from their disease by almost a third, the research showed.

Mid-life fitness also lowered the risk of being diagnosed with lung and bowel cancer, but apparently not prostate cancer.

The cardiorespiratory fitness (CRF) of almost 14,000 US men was measured using treadmill tests and their health from the age of 65 was monitored for 6.5 years.

During this period, 1,310 of the group were diagnosed with prostate cancer, 200 with lung cancer and 181 with bowel cancer.

The authors, led by Dr Susan Lakoski, from the University of Vermont in the US, wrote in the journal JAMA Oncology: "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 (cardiovascular disease) following a cancer diagnosis."

The research showed that high mid-life fitness was associated with a 55% reduced risk of lung cancer and a 44% lower risk of bowel cancer compared with men with low CRF readings.

However, the same association was not seen between mid-life CRF and prostate cancer.

This could simply be due to fitter men being more likely to request routine blood tests, creating a greater likelihood of prostate cancer diagnosis, said the authors.

For men who developed one of the cancers, high CRF in mid-life was associated with a 32% reduced risk of death from the disease. It also led to a 68% reduced risk of dying from cardiovascular disease.

The researchers added: "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."