A significant new study is showing that men who kept a high level of fitness in their midlife may have a lower overall risk of death from certain types cancers as they age.

Cardio Exercise Decrease Men's Cancer Risk

This study was published in the journal JAMA Oncology and led bby Dr. Susan Lakoski and her research team at the University of Vermont, Burlington.

"Men who are physically fit are expected to have lower levels of [cancer-related] sex hormones, enhanced immunity and lower inflammation," said lead researcher Dr. Lakoski, an assistant professor of medicine at the University of Vermont.

Key Findings

• Evaluated 14,000 men from 1971-2009
• Men specifically would reduce their risk once they hit the age of 65 or older
• Biggest benefit compared to men who maintained low cardio respiratory fitness against treadmill tests
• Men diagnosed with a cancer during Medicare age (65 years and over), the risk of dying from it was also reduced by high midlife fitness.
• These men with cancer were also considerably less likely to die from cardiovascular causes

• Over an average of 6.5 years of follow-up, 1,310 of the nearly 14,000 men were diagnosed with prostate cancer, 200 with lung cancer and 181 men with colon cancer.

• The fittest men had a 55 percent lower risk of lung cancer and a 44 percent lower risk of colon cancer, compared with unfit guys, the study found.
  They also had a 32 percent lower risk of dying if they did develop lung, colon or prostate cancer, the researchers said.

Reduced Risk Lung and Colon Cancer

For specific types of cancer, high cardiorespiratory fitness, compared with the least fit men, resulted in risk being lowered by:

• 55% for lung cancer
• 44% for colorectal cancer

No Reduced Risk for Prostate Cancer

Surprisingly, however, the study found no benefit for reducing the risk of prostate cancer.

The study actually showed a higher risk of prostate cancer associated with men who kept highly fit, but the authors look to other findings that may explain this "interesting" result.

• Men with higher cardio respiratory fitness may also be more likely to get screened or to take part in preventive health consultations, and so may simply show higher rates of diagnosis

The researchers were surprised that the risk for developing prostate cancer wasn't lower for the fitter guys, however.

It's possible that fit men are more likely to have frequent prostate screenings and, therefore, greater opportunity to be diagnosed withprostate cancer, Lakoski explained.

"Importantly, fit men who developed prostate cancer in the current study had a lower risk of dying of cancer or cardiovascular disease," she said. "This speaks to the importance of being fit in midlife to improve survival, even if a man ultimately develops lung, prostate or colorectal cancer."

Exercise Decreases Heart Disease & Stroke Risk

We already know that exercise significantly reduced the risk of heart disease and stroke. However the researchers of this study believe their findings arethe first to demonstrate a predictive relationship between levels of fitness and cancer incidence in addition to the study's cardiovascular disease results.

"These findings provide further support for the effectiveness of cardiorespiratory fitness assessment in preventive health care settings.

Future studies are required to determine the absolute level of cardiorespiratory fitness necessary to prevent site-specific cancer as well as evaluating the long-term effect of cancer diagnosis and mortality in women."

Where do we go from here?

Dr. Lakowski  stressed that this study shows an association between fitness and protection from cancer, not necessarily a cause-and-effect relationship.

"Future studies are needed to test these results across all major cancers in men and women, and also address how much an individual must change their fitness to see cancer prevention benefit," she said.

Evidence is growing that lifestyle behaviors influence cancer diagnoses years or decades later, the researchers said in background notes. While the link between fitness and heart protection is well-established, less is known about the connection between heart fitness and cancer, they said.