C-reactive protein — a marker of inflammation
circulating in the blood already associated with increased
risk of heart disease — can also be used to identify
a person's risk of developing colon cancer, according to a
Johns Hopkins study.
Results of the study, published in the Feb. 4 issue of
the Journal of the American Medical Association,
showed that over an 11-year period, people with higher
levels of CRP in their blood (a median of 2.44 milligrams
per liter) were more likely to develop colorectal cancers
than those with low levels of CRP (a median of 1.94
"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 "Tate" P. Erlinger, lead author of the
study and an assistant professor of
Johns Hopkins. "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 colleagues studied the records of 22,887
adults who participated in the CLUE II study, conducted in
Washington County, Md., looking to identify those who
developed colon or rectal cancer. In the CLUE II
investigation, named for its campaign, "Give Us a Clue to
Cancer and Heart Disease" and started between May and
October 1989, study volunteers provided a blood sample and
completed a brief health questionnaire. They since have
been followed by additional questionnaires and tracking
Comparing the CLUE II medical records with the
Washington County and Maryland State cancer registries, the
Hopkins team noted 172 people who were diagnosed with
either colon or rectal cancer following their initial date
of blood draw through December 2000. Of these, 131 had
colon cancer and 41 had rectal cancer. Researchers then
compared the health records of each of these individuals
with those of up to two healthy volunteers who had joined
the study at the same time, using the healthy volunteers as
a control group.
Median CRP 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). By
contrast, CRP concentrations were not significantly
different between cases of rectal cancer (1.79 mg/L) and
the controls (1.81 mg/L).
The study also found that:
The odds of developing colorectal
cancers increased progressively with higher concentrations
of CRP. Overall, people in the highest fourth of CRP had
twice the risk of developing colorectal cancer, and 2.5
times the risk of developing colon cancer, as those in the
Among nonsmokers, those in the
highest fourth of CRP were 2.5 times as likely to develop
colorectal cancer, and 3.5 times as likely to develop colon
cancer, as those in the lowest fourth.
Those who had taken either aspirin
or nonsteroidal anti-inflammatory agents within the 48
hours prior to blood draw had a reduced risk of colorectal
The association of inflammation
with colon cancer was unrelated to diabetes, going against
the belief that diabetes acts as the mediator between
inflammation and cancer risk.
Erlinger notes 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.
The study was supported by grants from the Maryland
Cigarette Restitution Fund, the National Institutes of
Health and the American Institute for Cancer Research.
Co-authors were Elizabeth A. Platz and Kathy J. Helzlsouer,
both of Hopkins, and Nader Rifai, of Harvard Medical