Cardiovascular fitness in middle-aged men reduced cancer risk, mortality

Middle-aged men who demonstrated increased levels of cardiovascular fitness were at lower risk for developing and dying of colorectal and lung cancers later in life, according to results of a 20-year prospective study.

Perspective from Sandra M. Swain, MD

“It is well accepted that fitness is a powerful way to predict cardiovascular disease and survival, and there are several benefits of measuring fitness. Unfortunately, little is known about fitness as a predictor for cancer incidence and subsequent outcomes in patients who develop cancer,” Susan Lakoski, MD, assistant professor of medicine at the University of Vermont, said during a press conference held to highlight several studies that will be presented at the ASCO Annual Meeting. “It is important to identify robust predictive markers … given cancer incidence is projected to increase over the next 2 decades, and patients are now expected to live sufficiently long to be at risk for noncancer-related mortality, specifically cardiovascular disease.”

Lakoski and colleagues conducted the Cooper Center Longitudinal Study to assess the association between baseline fitness levels — calculated during a specialized preventive checkup visit — and the risk for prostate, lung and colorectal cancer.

The analysis included 17,049 men with a mean age of 50 years.

The fitness test included walking on a treadmill at altered speed and elevation. Researchers recorded performance measures in metabolic equivalents.

At the median 20-year follow-up, researchers assessed Medicare claims data to identify study participants who subsequently developed lung, colorectal or prostate cancer.

Data indicated that 2,332 men were diagnosed with prostate cancer, 276 developed colorectal cancer and 277 were diagnosed with lung cancer. Researchers reported 347 cancer-related deaths and 159 deaths caused by cardiovascular disease.

After adjusting for smoking history, BMI, age and other factors, men categorized as most fit during the baseline fitness test were at 68% lower risk for lung cancer and 38% lower risk for colorectal cancer compared with those characterized as least fit. Fitness level did not significantly reduce risk for prostate cancer.

Among men who developed cancer, those considered more fit during middle age were at reduced risk for dying of lung, colorectal and prostate cancers, as well as cardiovascular disease. A 1 metabolic unit improvement in fitness reduced the risk for cancer-related mortality by 14% and cardiovascular disease-related mortality by 23%, researchers wrote.

Men who were not obese but still had a low fitness level were still at increased risk for cancer and cardiovascular disease, the researchers wrote.

“Fitness is a strong, independent predictor of incident lung and colorectal cancer in men and is a robust predictor of cause-specific mortality in older men diagnosed with lung, prostate or colorectal cancers,” Lakoski said. “These findings provide support for the utility of measuring fitness in the preventive health care setting to determine cancer risk and prognosis after cancer. Future studies are needed to test these results across all major cancers in men and women.”

For more information:

Lakoski SG. Abstract #1520. Scheduled for presentation at: ASCO Annual Meeting; May 31-June 4, 2013; Chicago.

Disclosure: Lakoski reports no relevant financial disclosures.

Perspective

Sandra M. Swain, MD

We've known that poor fitness predicts future cardiovascular disease, but this is one of the first studies to explore fitness as a marker for future cancer risk and outcomes. I think a really interesting finding was men who were not obese were at increased risk for cancer if they were not fit, which suggests that everyone can benefit from improving their fitness.

Sandra M. Swain, MD

ASCO President

Medical director, Washington Cancer Institute

MedStar Washington Hospital Center

Disclosures: Swain reports no relevant financial disclosures.