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Background: Infection with JC virus has been proposed as a risk factor for colorectal cancer. A nested case-control study was conducted to evaluate the association between prediagnostic JC virus antibodies and the risk of incident colorectal cancer and adenomas., Methods: Two research serum banks were established in Washington County, MD in 1974 and 1989, with the collection of blood samples from >45,000 volunteers. Incident colorectal cancer cases diagnosed through 2006 (n = 611) were identified among participants by linkage to population-based cancer registries, contributing 729 pairs of observations. Cases of adenomatous polyps (n = 123) were identified from participants of the 1989 cohort who reported having a colonoscopy-detected adenoma at follow-up through 2000 with histology confirmed through medical record review. One control was matched to each case on age, sex, race, and date of blood draw, and, for adenoma controls, date of endoscopy. IgG antibodies to JC virus were measured using virus-like particle ELISA. Associations between JC virus seropositivity and colorectal cancer and adenomas were estimated using conditional logistic regression., Results: Overall, there was no association between antibodies to JC virus and colorectal cancer [odds ratio (OR), 0.91; 95% confidence interval (95% CI), 0.71-1.17]. However, a statistically significant positive association between JC virus seropositivity and subsequent adenoma diagnosis was observed among males (OR, 2.31; 95% CI, 1.20-4.46), whereas a statistically significant inverse association was observed among females (OR, 0.31; 95% CI, 0.14-0.67; P for interaction = 0.01), after adjustment for baseline smoking and body mass index., Conclusions: Overall, JC virus seropositivity was not associated with colorectal cancer development up to 31 years later. Future studies are needed to confirm the adenoma findings.

Objective: Circulating C-reactive protein concentration has been associated with colorectal cancer in some studies. Whether C-reactive protein is associated with earlier steps in the natural history of this cancer has not been published (aside from an abstract). Thus, we evaluated the association between plasma C-reactive protein concentration and development of colorectal adenoma in a nested case-control study., Methods: Colorectal adenoma cases (n = 135) and matched controls (n = 269) who had a negative sigmoidoscopy or colonoscopy were identified between baseline in 1989 and 2000 from among participants in the CLUE II cohort of Washington County, Maryland. Cases were confirmed by medical record review. Controls were matched with cases on age, sex, race, date of blood draw, time since last meal, and type of endoscopy. The odds ratio (OR) of adenoma was estimated from conditional logistic regression models., Results: C-reactive protein concentrations were similar between colorectal adenoma cases and controls (median C-reactive protein, 1.31 vs. 1.38 mg/l; p = 0.13). The OR of colorectal adenoma among those in the highest fourth (>2.95 mg/l) of C-reactive protein concentration compared with the lowest fourth (<0.65 mg/l) was 0.61 (95% confidence interval, 0.29-1.25; p for trend = 0.25)., Conclusions: Pre-diagnostic plasma C-reactive protein concentration was not associated with an increased risk of colorectal adenoma. More work is needed to determine whether C-reactive protein is a valid marker of intra-colonic inflammation, and whether such inflammation contributes to the etiology of colorectal neoplasia.