Incidence data derive from population-based cancer registries. These may cover entire national populations but more often cover smaller, subnational areas and, particularly in developing countries, only major cities. In 2006, about 21% of the world population was covered by population-based cancer registries, with sparse registration in Asia (8% of the total population) and in Africa (11%).1 When considering data of good quality (for example, datasets included in the latest volume (IX) for the Cancer Incidence in Five Continents (CI5)
series of the IARC12), these percentages are even lower: only 8% of the world population is covered by cancer registries that match the CI5 inclusion criteria, 4% of which are located in Asia with only 1% in Africa. While the information from most of the developing countries might not meet the specific criteria for quality set for inclusion in CI5,13 this information is still of unique importance as it often remains the only relatively unbiased source of information available on the profile of cancer. Incidence data are generally associated with some delay as they require time to be compiled and published, but recent information can often be found in routine reports from the registries themselves, commonly available via their websites.