Patients in Hong Kong who were newly diagnosed with coronary artery disease had nearly twice the prevalence of colorectal tumors and cancers, with this association stronger in persons who had smoked or have the metabolic syndrome, according to a study in the September 26 issue of JAMA.
Colorectal cancer is the second most prevalent cancer worldwide, with an estimated 1 in 20 healthy individuals eventually developing the disease. Coronary artery disease (CAD) is the leading cause of death in the United States and other industrialized countries, according to background information in the article. Colorectal neoplasm ("precancerous" tumors or cancer) and coronary artery disease (CAD) share similar risk factors, and their co-occurrence may be associated.
Annie On On Chan, M.D., Ph.D., of the University of Hong Kong, China, and colleagues investigated the prevalence of colorectal cancer and colorectal neoplasms in patients with newly diagnosed CAD. Participants in the study were from Hong Kong and were recruited for screening colonoscopy after undergoing coronary angiography for suspected CAD from November 2004 to June 2006. Presence of CAD (n = 206) was defined as at least 50 percent diameter narrowing in any one of the major coronary arteries; otherwise, patients were considered CAD-negative (n = 208). An age- and sex-matched control group was recruited from the general population (n = 207).
The researchers found that colorectal neoplasms and advanced lesions were more prevalent (34.0 percent and 18.4 percent, respectively) in the CAD-positive group than in the CAD-negative (18.8 percent and 8.7 percent) and general population (20.8 percent and 5.8 percent) groups. The prevalence of cancer was 4.4 percent, 0.5 percent, and 1.4 percent, in the CAD-positive, CAD-negative, and general population groups, respectively. 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.
Regarding the association between these two diseases, the authors speculate: "Both colorectal neoplasm and CAD probably develop through the mechanism of chronic inflammation. Inflammation is now recognized as being pivotal in the pathogenesis of atherosclerosis and, hence, CAD. Colorectal cancer is also thought to progress through the pathway of inflammation."