Approximately 20% of all human cancers worldwide have been associated with infectious agents. This percentage is likely to be higher in low-resource countries where, due to socioeconomic conditions, infections are more frequent and health care surveillance is less available than in high-resource countries. Based on a vast number of biological and epidemiological studies, the International Agency for Research on Cancer (IARC) has classified six viruses and one bacterium as human carcinogens: high-risk mucosal human papillomavirus (HPV) types, hepatitis C virus (HCV), hepatitis B virus (HBV), human T-lymphotropic virus type I (HTLV-1), Epstein-Barr virus (EBV), Kaposi sarcoma-associated herpesvirus (KSHV), and the bacterium Helicobacter pylori.
The 20% estimate of pathogen-associated cancers may be rather low, and new evidence supports the involvement of additional infectious agents in human carcinogenesis. A recently discovered human polyomavirus, Merkel cell polyomavirus (MCPyV), is associated with a rare tumour, Merkel cell carcinoma. Early epidemiological studies suggest that infection with MCPyV is widespread in humans, and additional tumour associations may yet be discovered. Ongoing studies concerning a subgroup of HPV types that infect the skin suggest their involvement, together with ultraviolet radiation (or solar exposure), in the development of non-melanoma skin cancer (NMSC) in normal populations.
This meeting is a joint IARC/DKFZ initiative that will focus on discussions and the critical evaluation of the epidemiology, immunology, and biology of cancer-associated viruses. The meeting programme emphasizes new HPV-related cancers and newly discovered human polyomaviruses, although advances concerning other pathogens will be incorporated as they arise.