title: Oral contraception and the risk of hepatocellular carcinoma.
abstract: OBJECTIVE
  We performed a meta-analysis of observational epidemiological studies to examine the association between oral contraceptives (OC) and hepatocellular carcinoma (HCC).
  
  
  METHODS
  Two independent researchers conducted PubMed searches followed by systematic abstraction of studies that compared OC use between patients with HCC and a group of controls. Pooling of ORs was conducted using a random effects model. Heterogeneity and publication bias among studies were examined.
  
  
  RESULTS
  Twelve case-control studies that included 739 cases and 5223 controls met the inclusion and exclusion criteria. The pooled estimate of ORs (age- and sex-matched only) from all 12 studies was 1.57 (95% CI=0.96-2.54, p=0.07) with a heterogeneity of I(2)=39.9. Exclusion of one large multi-national European study decreased the heterogeneity to I(2)=16.9 and increased the pooled OR to 1.70 (95% CI=1.12-2.59, p=0.01). Eight studies reported adjusted ORs (in addition to age and sex); the pooled estimate was 1.45 (95% CI=0.93-2.27, p=0.11) with a heterogeneity of I(2)=20.4. Only few studies identified or adjusted for other HCC risk factors. Six studies showed a significant 2- to 20-fold increase in HCC risk with longer durations of OC use; however, the reporting was too inconsistent to allow meta-analysis.
  
  
  CONCLUSIONS
  The evidence is inconclusive to establish a relation between oral contraceptives and the risk of hepatocellular carcinoma. Future studies should focus on the duration, intermittency, and recency of OC use.
authors.affiliation: Sections of Gastroenterology and Health Services Research at the Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine, 2002 Holcombe Blvd., Houston, TX 77030, USA.
authors.forename: Shail
authors.initials: S
authors.lastname: Maheshwari
authors.forename: Amrou
authors.initials: A
authors.lastname: Sarraj
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kramer
authors.forename: Hashem B
authors.initials: HB
authors.lastname: El-Serag
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000453:epidemiology*; D016022:Case-Control Studies; D003276:Contraceptives, Oral / Q000008:administration & dosage*; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology; D006801:Humans; D008113:Liver Neoplasms / Q000453:epidemiology*; D012307:Risk Factors
chemical_list: D003276:Contraceptives, Oral