Geographic and income variations in age at diagnosis and incidence of chronic myeloid leukemia.

Developing countries have a younger population of CML patients than developed countries. Patterns of age at diagnosis and incidence by geography and gross national income (GNI) are not well understood. A population-based descriptive study was conducted using data from the International Agency for Research on Cancer's population-based registry compilation. Geographical regions were classified according to the United Nations World Macro Regions and Components. Age-Standardized Incidence Rates (ASR) were adjusted to the World Standard Population. Poisson regression was used to assess age-specific interactions. 57.2% were male among 33,690 diagnoses. Median age at diagnosis was lowest in Africa and Asia (47 years) and highest in Oceania (72 years). ASR was lowest in African males (0.61 per 100,000) and Asian females (0.55 per 100,000) and highest in Oceania males and females (1.78 and 0.96 per 100,000, respectively). A significant interaction (p < 0.0001) between age (<50 years and >50 years) and region exists; no significant differences were seen by region in the <50 age-group while significant differences by region exist in the >50 age group. Population-based estimates suggest that the median age at diagnosis and incidence varies by region. Geographic and income heterogeneity suggest an important effect of environment that warrants further studies.