Inflammatory Markers Are Associated with Risk of Colorectal Cancer and Chemopreventive Response to Anti-Inflammatory Drugs

Abstract

BACKGROUND and AIMS: Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) lower the risk of colorectal cancer (CRC). We investigated whether plasma inflammatory markers were associated with risk of CRC and if use of anti-inflammatory drugs was differentially associated with risk of CRC according to levels of inflammatory markers. METHODS: We measured levels of high-sensitivity C-reactive protein (CRP), interleukin (IL)-6, and the soluble tumor necrosis factor receptor 2 (sTNFR-2) in blood samples from 32,826 women, collected from 1989 to 1990. Through 2004, we documented 280 cases of incident CRC; each case was matched for age to 2 randomly selected participants without cancer (controls). Information on anti-inflammatory drug (aspirin and NSAIDs) use was collected biennially. RESULTS: Compared with women in the lowest quartile of plasma levels of sTNFR-2, women in the highest quartile had an increased risk of CRC (multivariate relative risk [RR], 1.67; 95% confidence interval [CI], 1.05-2.68; P for trend = .03). Among women with high baseline levels of sTNFR-2, those who initiated aspirin/NSAID use after blood collection had significant reductions in subsequent risk of CRC (multivariate RR, 0.39; 95% CI, 0.18-0.86). In contrast, among women with low baseline levels of sTNFR-2, initiation of aspirin/NSAID use was not associated with significant risk reduction (multivariate RR, 0.86; 95% CI, 0.41-1.79). Plasma levels of CRP and IL-6 were not significantly associated with CRC risk. CONCLUSIONS: Plasma levels of sTNFR-2, but not CRP or IL-6, are associated with an increased risk of CRC. Anti-inflammatory drugs appear to reduce risk of CRC among women with high, but not low, baseline levels of sTNFR-2. Certain subsets of the population, defined by inflammatory markers, may obtain different benefits from anti-inflammatory drugs.