Bacteria, viruses and parasites cause around 2m cases of cancer in the world each year, experts believe. Of the 7.5m global deaths from cancer in 2008, an estimated 1.5m may have been due to potentially preventable or treatable infections. Scientists carried out a statistical analysis of cancer incidence to calculate that around 16% of all cancers diagnosed in 2008 were infection-related. The proportion of cancers linked to infection was three times higher in developing countries than in developed ones.
Key cancer-causing infectious agents include human papillomavirus (HPV), the gastric bug Helicobacter pylori and the hepatitis B (HBV) and C viruses.