Global Cancer Incidences are Substantially Under-estimated Due to Under-ascertainment in Elderly Cancer Cases

Background: The cancer incidence in developing countries is 7-16% under-estimated due to underascertainmentof elderly cases in cancer registry data. The global cancer incidence, as a mixture of incidence inall countries, could thus be under-estimated as well. This study was conducted to report corrected global cancerincidence.
Methods: The corrected rate in age group 65+ for “All sites excluding skin cancer” was calculated bysumming 1/3 of the original age-specific rate and 2/3 of anti-logarithm of “the predicted value of the logarithmof rate in age group 65+” multiplied by a sex-specific coefficient. Cancer data were obtained from GLOBOCAN2002.
Results: The global cancer incidence estimate by the GLOBOCAN 2002 was 8.7% (men 13.3%; women3.4%) under-estimated due to under-ascertainment in elderly cases, which means, worldwide, new cancer casesin 2002 were 11,810,000 (6,574,000 men; 5,236,000 women), topping the original estimate by 1 million.
Conclusions: The global cancer incidence estimate is substantially under-estimated due to under-ascertainmentin elderly cases. This correction is performed mathematically; the results, however, emphasize the need forpractical strategies to prevent under-ascertainment in the elderly.