The team at the University of Hong Kong believe unhealthy habits and inflammation may be the link between the two diseases.

Both illnesses share several risk factors such as smoking, high-fat diet, obesity, diabetes, high blood pressure, and a sedentary lifestyle.

While coronary artery disease (CAD) is the leading cause of death in the United States and other developed countries, colorectal cancer is the second most common cancer worldwide.

Experts say colorectal neoplasm (precancerous tumors or cancer) and coronary artery disease share similar risk factors, and there is possibly a link between their co-occurrence.

Dr. Annie Chan and her colleagues conducted a study which investigated this perceived link between the prevalence of colorectal cancer and colorectal neoplasms in patients with newly diagnosed CAD.

The participants were all from Hong Kong and were recruited for screening colonoscopy after undergoing coronary angiography for suspected CAD between November 2004 to June 2006.

The presence of CAD was defined as at least a 50 percent diameter narrowing in any one of the major coronary arteries; the group were compared to an age and sex-matched control group recruited from the general population.

The researchers discovered that 34 percent of the CAD group also had cancerous colon tumors, compared to some 20 percent of patients found to have tumors who were free of heart disease in the control group.

Fifty percent of the cancers in the CAD-positive participants were early stage.

The researchers also found that both the metabolic syndrome and history of smoking were strong independent predictive factors for the positive association between advanced lesions and CAD.

The authors suggest that both colorectal neoplasm and CAD probably developed as a result of chronic inflammation which is recognized as being pivotal in the pathogenesis of atherosclerosis and therefore CAD.

Colorectal cancer is also thought to progress through the pathway of inflammation.

The authors say the cholesterol-lowering drugs statins appear to have a deterrent effect on both illnesses, perhaps because the drugs reduce inflammation; Aspirin too appears to reduce the risk.

The study is published in the September 26 issue of JAMA.