The incidence of and mortality from leukaemias in the UK: a general population-based study

Background: The acute and chronic leukaemias constitute about 2.5% of all newly diagnosed malignancies and kill over 4000 people/year in the UK, yet there is little accurate up-to-date data on how the incidence of and mortality from leukaemias vary with socio-economic status in the UK. We aimed to quantify the incidence of and mortality from leukaemias in the UK and their variation with gender, age, year of diagnosis as well as socio-economic status. Methods: All incident cases of leukaemia were identified in 'The Health Improvement Network' (THIN) General Practice dataset. Crude incidence rates and incidence rate ratios (using Poisson Regression) stratified by age, gender, year of diagnosis and socio-economic status were calculated. Median survival and hazard ratios for risk of death (using Cox regression) were then calculated, and stratified in a similar manner. Results: A total of 4162 cases of leukaemia were identified, 2314 (56%) of whom were male. The overall incidence of leukaemia was 11.25 per 100 000 person-years. The age and gender distributions of ALL, AML, CLL and CML were similar to UK cancer registry data. The incidence of leukaemias was independent of socio-economic class. Median survival from leukaemia was 6.58 years and mortality increased with increasing age at diagnosis. The prognosis in AML was dismal and worsened with increasing socio- economic deprivation. For other leukaemias mortality was independent of socio- economic status. Conclusion: This is the first general population study to describe the incidence of and mortality from leukaemias in the UK by socio- economic status. Similar mortality across socio- economic gradients in the leukaemias studied suggests equal access to and uptake of services. The exception to this was in AML, where poorer survival in AML patients from lower socio- economic classes may represent a class bias in treatment offered and/or greater co-morbidity in these patients, and warrants further exploration.