A prospective study of plasma inflammatory markers and risk of colorectal cancer in men.

BACKGROUND: Chronic inflammation may mediate risk of colorectal cancer (CRC); however, the association between circulating inflammatory markers and risk of CRC has been inconsistent. METHODS: We prospectively evaluated the association of plasma C-reactive protein (CRP), interleukin-6 (IL-6), and the soluble tumour necrosis factor receptor 2 (sTNFR-2) with incident CRC among 274 cases and 532 matched controls nested in the Health Professionals Follow-up Study. RESULTS: Multivariate relative risk (RR) of CRC comparing the extreme quartiles of plasma IL-6 was 1.54 (95% confidence interval (CI), 0.99-2.40; P(trend)=0.02). However, after excluding cases diagnosed within 2 years of blood draw, this association was not statistically significant (RR=1.26, 95% CI, 0.78-2.05; P(trend)=0.21). In analyses restricted to cases diagnosed at least 2 years after blood draw, the association of IL-6 with CRC appeared to differ by body mass index such that the significantly positive association was only present among lean individuals (P(interaction)=0.03). We did not observe any significant association between CRP or sTNFR-2 and CRC. CONCLUSION: Plasma inflammatory markers are not generally associated with risk of CRC among men. However, the possibility that plasma IL-6 is associated with increased risk of CRC among lean men requires further investigation.