Elevated C-reactive protein not associated with cancer risk

Gene variants associated with increase circulating levels of C-reactive protein, a marker of inflammation, are not associated with an increased risk of cancer.

Researchers used a Mendelian randomization design to examine if polymorphisms were linked to increased plasma C-reactive protein levels and whether the increase was linked to increased cancer risk. The study population included 10,215 participants from the prospective Copenhagen City Heart Study and 36,403 participants from the cross-sectional Copenhagen General Population Study. All participants had been genotyped for CRP single-nucleotide polymorphisms.

None of the C-reactive protein single-nucleotide polymorphisms identified were associated with an elevated risk for cancer in either group of participants.

The nine most frequent genotype combinations were associated with a 72% (95% CI, 58-87) increase in C-reactive protein levels, but was not associated with an increased risk of cancer among either study group.

When data from the two groups were combined, the OR for a genetically induced doubling of the plasma C-reactive protein levels was 0.94 (95% CI, 0.81-1.08). The HR for cancer for a doubling of the plasma C-reactive protein level was 1.09 (95% CI, 1.03-1.14).

C-reactive protein may possibly be excluded as a cause of cancer; although, inflammation may lead to cancer, and increased C-reactive protein levels may potentially be used to predict the risk for certain cancer subtypes, according to researchers.

“The study is an elegant example of how genetic variants that have a functional impact can be used to explore association between environmental factors and disease, and specifically to identify and control for confounding factors…,” Paolo Boffetta, MD, MPH, of the International Prevention Research Institute, in Lyon, France, wrote in an accompanying editorial.

“An important lesson of this study is, not unexpectedly, that validation of etiologic cancer biomarkers, in view of their possible application in the population, require large carefully conducted prospective studies,” he wrote.

Allin KH. J Natl Cancer Inst. 2009;102:doi:10.1093/jnci/djp459.