文摘
Purpose Many studies have evaluated the associations between pre-diagnostic circulating C-reactive protein (CRP), interleukin-6 (IL-6) and colorectal cancer risk, but their results are inconsistent. We therefore conducted a meta-analysis to investigate these associations. Methods A comprehensive literature search up to October 2013 was undertaken in PubMed. Pooled relative risk (RR) estimates and 95?% confidence intervals (CIs) were used to calculate estimated effect. Results Eighteen studies on CRP comprising a total of 4,706 colorectal cancer cases were included in this meta-analysis. The summary RR of colorectal cancer for one unit change in natural logarithm (ln) CRP was 1.12 [95?% CI (1.05-.21)]. There was statistically significant heterogeneity among studies (p?=?0.006; I 2?=?51.7?%). After excluding the studies contributing most to the heterogeneity, summary estimate was essentially unchanged. In addition, the association was significant for colon cancer [RR?=?1.13, 95 % CI (1.05-.21)], not for rectal cancer [RR?=?1.03, 95 % CI (0.90-.17)]. We also found that CRP was significantly associated with increased risk of colorectal cancer among men, but not among women. There were six studies on IL-6 that involved a total of 1,068 colorectal cancer cases. The pooled RR of colorectal cancer for one unit change in ln IL-6 was 1.10 (95?% CI 0.88-.36), and no statistically significant heterogeneity was found (p?=?0.175; I 2?=?34.8?%). Conclusion Our results suggest that pre-diagnostic circulating CRP is associated with increased risk of colorectal cancer. However, there is no significant association between IL-6 and colorectal cancer risk.