Dr Shail Maheshwari and colleagues from Texas, USA performed a meta-analysis of observational epidemiological studies to examine the association between oral contraceptives and hepatocellular carcinoma.
The team reported that 2 independent researchers conducted PubMed searches followed by systematic abstraction of studies.
The studies compared oral contraceptives use between patients with hepatocellular carcinoma and a group of controls.
|6 studies showed a 2- to 20-fold increase in hepatocellular carcinoma risk|
|Journal of Hepatology|
The team pooled the odds ratios using a random effects model.
Heterogeneity and publication bias among studies were examined.
The researchers identified 12 case-control studies that included 739 cases, and 5223 controls met the inclusion and exclusion criteria.
The pooled estimate of odds ratios from all 12 studies was 1.6 with heterogeneity present.
The team found exclusion of 1 large multi-national European study decreased the heterogeneity, and increased the pooled odds ratio to 1.7.
The researchers observed that 8 studies reported adjusted odds ratios, giving a pooled estimate of 1.5.
Only few studies identified or adjusted for other hepatocellular carcinoma risk factors.
The team noted that 6 studies showed a significant 2- to 20-fold increase in hepatocellular carcinoma risk with longer durations of oral contraceptives use.
However, the reporting was too inconsistent to allow meta-analysis.
Dr Maheshwari's team concluded, "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 oral contraceptives use."