Burden of cancer attributable to infection

PL05-01

Frontiers in Cancer Prevention Research, Sixth Annual AACR International Conference
 5-8 December 2007, Philadelphia, USA
 Burden of cancer attributable to infection
 Silvia Franceschi
 International Agency for Research on Cancer, Lyon, France
 The most recent estimates attributed 18% of cancer (1.9 million cases) worldwide in 2002 to infectious agents (Parkin et al, 2006). This fraction varies substantially between developed (7.7%) and developing (26.3%) countries. Estimates of infection-associated cancers are, for a number of reasons, conservative ones: 1) the prevalence of infection in cancer patients and in the general population (on whom the computation of attributable risks is based) are not always accurate and generally tend to be underestimated; 2) carcinogenic and non (or less) carcinogenic types of infection are not well distinguished; 3) infections may be involved in the aetiology of other cancers (e.g., skin, gallbladder, colon, bladder, and certain types of lymphomas and leukaemias).
 The most important contributors to these fractions are human papillomavirus (HPV, 5% of the cancer burden, nearly 10% among women, worldwide), hepatitis B and C viruses (HBV and HCV, 5%) and Helicobacter pylori (Hp, 6%). These infections will be discussed in greater detail. HPV (Clifford et al, 2003) and HBV (Raza et al, 2007) represent good examples of well understood infections against which highly efficacious preventive vaccines have become available (Saslow et al, 2007). HCV is responsible for a higher fraction of hepatocellular carcinoma than HBV in the vast majority of developed countries, but also in several developing countries, on account of increases in HCV transmission through unsafe injection practices (Raza et al, 2007). In respect to Hp, improvements in the possibility to distinguish cagA-positive from cag-A-negative strains are leading to a steady rise in the apparent strength of the association (Plummer et al, 2007) and might, ultimately, increase substantially the fraction of gastric cancer attributed to Hp.
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