Feb. 3, 2004 -- Elevated blood levels of the inflammation marker C-reactive protein (CRP) have been linked to an increased risk for heart attack and stroke. Now early research suggests the protein may also play a role in the development of colon cancer.
In a study involving almost 23,000 people followed for roughly a decade, researchers found CRP concentrations in blood were higher among those who later developed colon cancer. Lead researcher Thomas Erlinger, MD, tells WebMD that the strength of the association was similar to that previously shown for heart disease.
While the findings add to the evidence linking inflammation with colon cancer risk, the Johns Hopkins investigator says more research is needed to determine if elevated C-reactive protein is a useful predictor of the risk of colon cancer. "The fact that we found this association is interesting, even though it does not prove a causal association between elevated CRP and colon cancer," Erlinger says.
Risk More Than Doubled
A cardiovascular epidemiologist, Erlinger says he decided to investigate the role of CRP in colorectal cancer because of the increasing evidence identifying inflammation as a risk factor for the disease.
The study included 22,887 adults followed from October 1989 to December 2000. A total of 172 colorectal cancer cases were identified during the period. The researchers compared these people's CRP levels at the beginning of the study with other participants of similar age, sex, and race who did not develop cancer.
C-reactive protein levels were much higher in those who later developed colon cancer. Compared with people with the lowest CRP levels, those with the highest were 2.5 times as likely to have a later diagnosis of colon cancer, but no increase in risk was seen for rectal cancer. The findings are published in the Feb. 4 issue of The Journal of the American Medical Association.
An Aspirin a Day?
Northwestern University oncologist Boris Pasche, MD, PhD, says while it is not clear from this study if C-reactive protein is a useful marker for colon cancer, it is increasingly evident that chronic inflammation plays a causal role in the disease.
In an editorial published along with the study, Pasche and co-author Charles Serhan, PhD, noted that prevention studies show low-dose aspirin and other nonsteroidal anti-inflammatory drugs help protect people at risk from developing colorectal cancer. Nonsteroidal anti-inflammatory drugs, or NSAIDs, are a class of pain relievers that includes ibuprofen, Advil, and Motrin but does not include Tylenol.
Anyone over 50 is considered to be at elevated risk for colorectal cancer, as are younger people with a family history of the disease.
"The correlation between low-dose aspirin and a decreased risk of colon cancer is well established," he tells WebMD. "Whether someone with a high CRP benefits more or less than the general at-risk population from this therapy remains to be seen."