Elevated levels of the inflammatory marker C-reactive protein predict a higher risk for colon cancer, according to an article in the February 4th issue of the Journal of the American Medical Association.
Over an 11-year follow-up period, people with higher blood levels of C-reactive protein (median, 2.44 mg/L) were more likely to develop colorectal cancer than people with low levels (median, 1.94 mg/L).

"Higher levels of C-reactive protein are linked to an increased risk of several apparently distinct, chronic diseases: heart disease, stroke, diabetes, and now colon cancer," said Thomas P. Erlinger, MD, MPH, lead author of the study. "However, it's not clear yet how or whether measuring C-reactive protein would fit into current screening and prevention strategies for colorectal cancer. Further studies should help answer these questions and help clarify the mechanism by which inflammation increases the risk of cancer."

Erlinger and his American colleagues studied the records of 22,887 adults who participated in a trial that began in 1989 to identify markers for people at risk for colorectal cancer. Of the total, 172 people were diagnosed with colon (131) or rectal (41) cancer after initial blood testing down in 2000. Researchers then compared the health records of each affected individual with those of up to two people who had joined the study at the same time and remained healthy.

Median C-reactive protein levels at baseline were higher among people who subsequently developed colon cancer (2.69 mg/L) than among those who remained free of disease (1.97 mg/L). In contrast, C-reactive concentrations were not significantly different between cases of rectal cancer (1.79 mg/L) and the controls (1.81 mg/L).

In addition, the American researchers found that the likelihood of developing colorectal cancer increased progressively with higher blood levels. Overall, people in the highest quarter of the population had 2.0 times the risk of developing colorectal cancer and 2.5 times the risk of developing colon cancer then people in the lowest quarter.

People who noted they had taken either aspirin or another nonsteroidal anti-inflammatory agent within the 48 hours prior to the baseline blood test had a reduced risk of colorectal cancer.

Finally, the researchers noted that the association of inflammation with colon cancer was unrelated to diabetes, suggesting that diabetes is not the mediator between inflammation and cancer risk.

Erlinger concluded that while these results should apply to the general population, most of the study population was Caucasian, so further studies should look at a more diverse group.