A new study has established – in real numbers – that cardio fitness significantly lowers the risk of developing colorectal and lung cancers.
It also found that people who developed these cancers, and were otherwise fit, were less likely to die than people with low fitness levels.
The study, headed by Dr Catherine Handy Marshall, from the John Hopkins School of Medicine, investigated 49,143 adults who underwent exercise stress testing from 1991 to 2009 and were followed for a median of 7.7 years.
Participants in the highest fitness category had a 77 per cent decreased risk of developing lung cancer and a 61 per cent decreased risk of developing colorectal cancer.
Much higher chance of cancer survival linked to fitness
Among those who developed lung cancer, those with the highest fitness had a 44 per cent decreased risk of dying following treatment.
Among adults who developed colorectal cancer, those with the highest fitness had an 89 per cent decreased risk.
“Our findings are one of the first, largest, and most diverse cohorts to look at the impact of fitness on cancer outcomes,” said Dr. Handy Marshall in a prepared statement.
Fitness testing is commonly done to establish heart problems and tolerance for exercise.
Stress-test patients urged to ask about cancer risk
Dr Handy Marshall advises that when people undergo a stress test – or already have done so – they could be informed “about the association of fitness with cancer risk in addition to what fitness levels mean for other conditions, like heart disease.”
Dr Handy Marshall noted that the benefits of exercise and fitness were on a sliding scale. People of moderate fitness still gained benefit in terms of lower risk and great chance of cancer survival. While those of poor fitness were at greatest risk.
While the study confirms an association between fitness and cancer risk, the precise mechanism is yet to be determined. But some of the answer is to be found in people who lack fitness – and tend to be overweight or obese, and burdened with unhealthy insulin levels, inflammation and compromised immunity.
All these conditions are known risk factors for cancer and other diseases. And the John Hopkins research is supported by previous research.
Previous research support the new findings
In 2015, scientists from the University of Vermont found that high cardiorespiratory fitness (CRF) in midlife was associated with a 55 per cent lower risk of lung cancer and a 44 per cent lower risk of colorectal cancer compared to men with low CRF.