title: C-reactive protein, interleukin-6 and the risk of colorectal cancer: a meta-analysis.
abstract: OBJECTIVE
  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 (1.05-1.21)]. 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 (1.05-1.21)], not for rectal cancer [RR = 1.03, 95% CI (0.90-1.17)]. 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 0.88-1.36), and no statistically significant heterogeneity was found (p = 0.175; I(2) = 34.8%).
  
  
  CONCLUSIONS
  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.
authors: School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009, China.
authors: Bo
authors: B
authors: Zhou
authors: Bin
authors: B
authors: Shu
authors: Jue
authors: J
authors: Yang
authors: Jing
authors: J
authors: Liu
authors: Tao
authors: T
authors: Xi
authors: Yingying
authors: Y
authors: Xing
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D002097:C-Reactive Protein / Q000378:metabolism*; D016022:Case-Control Studies; D003110:Colonic Neoplasms / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D015179:Colorectal Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D016001:Confidence Intervals; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D015994:Incidence; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D012004:Rectal Neoplasms / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; C508600:IL6 protein, human; D015850:Interleukin-6; D002097:C-Reactive Protein