Epidemiology

• CLL is the commonest type of leukaemia in the western world (1,2,3)
  • the annual incidence rate in this part of world is estimated to be of 4 per 100.000
  • it accounts for 40% of all cases of leukaemias in people over the age of 65 years
  • it is 20-30 times more commoner in Europe, Australasia and North American white and black populations than in India, China and Japan
• less than 5% of CLL are T cell type
• disease is diagnosed most commonly in the elderly
  • it is extremely rare before the age of 30 years
  • the median age at diagnosis is 69 years with 80% of patients diagnosed more than 60 years of age
  • the incidence increases to >30 per 100,000 per year at age of more than 80 years
• men are affected twice as commonly as women

The role of environmental factors is unclear. Genetic factors may be involved.

• there may be some overlap between CLL and the leukaemic phase of lymphomas.

References:

1. Eichhorst B, Robak T, Montserrat E, et al; ESMO Guidelines Committee. Chronic lymphocytic leukaemia: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2021 Jan;32(1):23-33.
2. Hallek M, Al-Sawaf O. Chronic lymphocytic leukemia: 2022 update on diagnostic and therapeutic procedures. Am J Hematol. 2021 Dec 1;96(12):1679-705.
3. Walewska R, Parry-Jones N, Eyre TA, et al. Guideline for the treatment of chronic lymphocytic leukaemia. Br J Haematol. 2022 Jun;197(5):544-57.