Epidemiology

• CLL is the commonest type of leukaemia in the western world
  • the annual incidence rate in this part of world is estimated to be of 4 per 100.000 (1)
  • 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 (1)
• 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 (1)
  • 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 (2)
• 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.

Reference:

• (1) Oscier D et al. Guidelines on the diagnosis and management of chronic lymphocytic leukaemia. Br J Haematol. 2004;125(3):294-317
• (2) Eichhorst B et al. Chronic lymphocytic leukaemia: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2010;21 Suppl 5:v162-4
• (3) Redaelli A et al.The clinical and epidemiological burden of chronic lymphocytic leukaemia. Eur J Cancer Care 2004;13:279–287.
• (4) Wallach (1992). Interp. of Diag. Tests. Little, Brown.
• (5) Jones (1992). Chronic Leukaemia. Med. Int. 97