Laboratory evidence of Helicobacter species infection in hepatocellular carcinoma

Chronic Helicobacter pylori infection is considered the main cause of gastric cancer and it has been associated to several extra-gastric manifestations. In addition, Helicobacter species (Helicobacter spp) have been associated to chronic liver disease progression and hepatocellular carcinoma (HCC) development, both in the animal model and in human beings. Helicobacter spp may be responsible of cancer development through both a direct mechanism involving the production of toxins causing hepatocellular damage and an indirect mechanism of induction of a chronic inflammatory state, a well-known risk factor of progression towards cancer. To date, most studies investigated Helicobacter spp presence in the liver tissue by means of PCR techniques targeting specific sequences of the 16S ribosomal DNA of the bacteria, while culturing the microorganism from the liver has always been difficult. For this reason, it is still to be proven whether the presence of DNA sequences of Helicobacter spp in the liver represents a true colonization or only a genomic trace related to an entero-hepatic circulation of the bacterium. Here, we review the current available data regarding the potential association between Helicobacter spp infection and HCC development addressing the issue concerning the detection methods for Helicobacter spp in liver tissue.