Staying Fit Could Ward Off Lung and Colorectal Cancer for Middle-Age Men

A large, 20-year prospective study shows that men aged 50 or older engaged in plenty of cardiovascular fitness have both a reduced risk of dying from lung and colorectal cancer-two of the most common cancers-and a reduced risk of developing these cancers. The results from this long-term study were presented at an American Society of Clinical Oncology (ASCO) press conference ahead of the 2013 annual meeting. Staying fit did not lower the risk of developing prostate cancer, but it did lower the risk of dying from prostate cancer.

“Men who were fit in middle age had a lower risk of dying from all three cancers we studied,” said presenter Susan Lakoski, MD, a cardiologist and epidemiologist at the University of Vermont.

While a healthy diet and active lifestyle correlate with better overall health and lower cancer risk, there are few studies on whether fitness can be a predictor of cancer incidence or cancer death. Exploring the link between cardiorespiratory fitness and cancer incidence and cancer death, participants in the study had their baseline cardiorespiratory fitness measured with exercise tolerance tests on treadmills at different inclines and speeds.

Risk of being diagnosed with lung or colorectal cancer was reduced by 68% and 38%, respectively, in men who were the most fit in the study relative to those who were the least fit over the 20-year period. The analysis was adjusted for factors such as age, body weight, and smoking history. Mortality declined with higher fitness level among men in the study.

“This is one of the first studies to explore fitness as a marker of future cancer risk and outcome, that is exciting,” said Dr. Sandra M. Swain, MD, professor of medicine, Georgetown University, and president of ASCO.

Cardiorespiratory fitness is a prognostic marker of cardiovascular disease and survival and reflects how well the heart, lungs, and blood system can coordinately deliver oxygen to the muscles during exercise.

“It is well accepted that fitness is a powerful way to predict cardiovascular disease and survival,” said Lakoski. According to Lakoski, fitness is an accurate marker of exercise. Fitness can also be accurately measured over time and is a good benchmark to compare patients of the same age.

Lakoski and colleagues followed 17,049 men in the Cooper Center Longitudinal Study (CCLS), a prospective and observational cohort study of participants at the Cooper Clinic in Dallas, Texas. The average age of men in the study was 50. Men in the study had preventive health examinations, including cardiorespiratory assessments.

Men in the study were divided into five fitness level groups based on their baseline fitness assessment.

When participants reached Medicare age, their records were assessed for prostate, lung, and colorectal cancer. Fitness didn’t significantly impact prostate cancer diagnosis risk.

A total of 2,885 men were diagnosed with prostate, lung, or colorectal cancer and 769 died of their cancer during the study period.

In those men who developed cancer, even a small improvement in fitness was associated with a 14% decrease in cancer mortality (P < .001) and a 23% reduction in cardiovascular mortality (P < .001).

The results of this study support using fitness measures in preventive health settings to determine both cancer risk and prognosis after a cancer diagnosis. Further studies are still needed to understand how fitness level can influence risk of other types of cancer and whether starting a fitness program in midlife can have a role in cancer prevention.