Middle-aged men can reduce their risk of developing lung and colorectal cancer by staying in shape, according to a new study presented at the 2013 meeting of the American Society of Clinical Oncology.

Furthermore, those who do develop those cancers - as well as prostate cancer - but are fit, may have a smaller risk of dying as a result.

“Fitness is a huge predictor of [cancer] risk,” Dr. Susan Lakoski, an assistant professor of internal medicine at the University of Vermont told HealthDay reporter Kathleen Doheny. “You need to be fit to protect yourself against a cancer diagnosis in older age.”

And while other studies have found physical activity protects against certain cancers, Lakoski explained that fewer studies have actually looked at the importance of fitness in predicting whether men would develop or die from cancers.

In all, Lakoski and her colleagues examined more than 17,000 men who were on average 50 years old via a single cardiovascular fitness assessment in Dallas.

The men walked on a treadmill as it changed speed and incline and their results were categorized into five groups from most to least fit, the latter of which were only able to last between 7.5 and 13.5 minutes walking, depending on age.

The researchers then analyzed Medicare claims data to identify those who developed had developed either lung, colorectal or prostate cancer.

On average, the follow-up period was 20 to 25 years.

In that period, 2,332 men developed prostate cancer, 276 developed colorectal cancer and 277 developed lung cancer.

Furthermore, during that same period, 347 men had died of cancer.

Ultimately, the men who ranked as the most fit had a 68 percent lower risk of lunch cancer and a 38 percent lower risk of colorectal cancer in comparison to those who performed worst in the fitness examine. And while their chance of developing prostate cancer did not decrease, their odds of dying from it did.

Fortunately, the benefits weren’t for the most fit only: those who were able to last an extra three minutes on the treadmill increased saw a 14 percent reduction in death due to cancer. However, those who were merely skinny but not fit did not appear to benefit in the same way as those who were fit.