title: Hepatitis B or C viral infection and risk of pancreatic cancer: a meta-analysis of observational studies.
abstract: OBJECTIVE
  To investigate if there is an association between hepatitis B virus (HBV) or hepatitis C virus (HCV) infection and the risk of pancreatic cancer.
  
  
  METHODS
  All relevant studies published before 11 October, 2012 were identified by a systematic search of MEDLINE, EMBASE, BIOSIS Previews and the Cochrane Library databases and with cross-referencing. The observational studies that reported RR or OR estimates with 95%CIs for the association between HBV or HCV and pancreatic cancer were included. A random-effects model was used to summarize meta-analytic estimates. The Newcastle-Ottawa quality assessment scale was applied to assess the quality of the methodology in the included studies.
  
  
  RESULTS
  A total of 8 eligible studies were selected for meta-analysis. Overall, chronic hepatitis B and inactive hepatitis B surface antigen (HBsAg) carrier state (HBsAg positive) had a significantly increased risk of pancreatic cancer with OR of 1.20 (95%CI: 1.01-1.39), especially in the Chinese population (OR = 1.30, 95%CI: 1.05-1.56). Past exposure to HBV (possible occult HBV infection) had an increased OR of pancreatic cancer risk (OR = 1.24, 95%CI: 1.05-1.42), especially among those patients without natural immunity [anti hepatitis B core (HBc) positive/hepatitis B surface antibody (anti HBs) negative], with OR of 1.67 (95%CI: 1.13-2.22). However, past exposure to HBV with natural immunity (anti-HBc positive/anti-HBs positive) had no association with pancreatic cancer development, with OR 0.98 (95%CI: 0.80-1.16), nor did the HBV active replication (hepatitis B e antigen positive status), with OR 0.98 (95%CI: 0.27-1.68). The risk of pancreatic cancer among anti-HBs positive patients was significantly lower than among anti-HBs negative patients (OR = 0.54, 95%CI: 0.46-0.62). Past exposure to HCV also resulted in an increased risk of pancreatic cancer (OR = 1.26, 95%CI: 1.03-1.50). Significant between-study heterogeneity was observed. Evidence of publication bias for HBV/HCV infection-pancreatic cancer association was not found.
  
  
  CONCLUSIONS
  Chronic HBV and HCV infection increases pancreatic cancer risk. Our findings underscore the need for more studies to confirm this potential relationship.
authors.affiliation: Department of Pathogen Biology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou 510515, Guangdong Province, China.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Xu
authors.forename: Jin-Jian
authors.initials: JJ
authors.lastname: Fu
authors.forename: Xiao-Li
authors.initials: XL
authors.lastname: Wang
authors.forename: Jia-Yong
authors.initials: JY
authors.lastname: Zhu
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Ye
authors.forename: Si-Dong
authors.initials: SD
authors.lastname: Chen
mesh_terms: D016009:Chi-Square Distribution; D019317:Evidence-Based Medicine; D019694:Hepatitis B, Chronic / Q000175:diagnosis / Q000453:epidemiology*; D019698:Hepatitis C, Chronic / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D064887:Observational Studies as Topic; D016017:Odds Ratio; D010190:Pancreatic Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D018570:Risk Assessment; D012307:Risk Factors
keywords: Hepatitis B; Hepatitis C; Meta-analysis; Observational studies; Pancreatic cancer