Primary biliary cirrhosis and cancer risk: A systematic review and meta-analysis

Several studies have indicated that primary biliary cirrhosis (PBC) may be associated with increased risk of some cancers, but the results are controversial. We conducted a systematic review of studies to examine the association of PBC with cancer risk by meta-analysis. We searched the PubMed and EMBASE databases for English-language studies published before November 2011. Studies were included if they reported relative risk estimates with 95% confidence intervals (CIs) or related data for the association between PBC and cancer risk. Approximately 16,300 PBC patients from several countries were included in this analysis. Of the 3510 titles identified, 16 publications involving 17 studies meeting the inclusion criteria were included in the meta-analysis. Compared with the general population, PBC patients had a significantly higher risk of overall cancer (pooled rate ratio [RR], 1.55; 95% CI, 1.28-1.83) and hepatocellular carcinoma (HCC) (pooled RR, 18.80; 95% CI, 10.81-26.79). For stomach and pancreas cancers, the results of one study that only examined male patients with PBC indicated that PBC patients had increased risk of stomach cancer and pancreatic cancer, whereas the results of other studies of mixed-sex patients showed no significant association. Therefore, despite inconsistent results, the meta-analysis could not be conducted for assessing the association. PBC was not significantly associated with increased risk of other cancers.The present systematic review and meta-analysis demonstrate that PBC is closely associated with a greater risk of overall cancer and HCC, but not with other cancers. The data regarding the association between PBC and risks of several cancers need to be further confirmed in future studies.