The most common type of leukemia in older adults is:

• A. Acute myeloid leukemia.
• B. Acute lymphocytic leukemia.
• C. Chronic myeloid leukemia.
• D. Chronic lymphocytic leukemia.

Answer: (D)

In older adults, the most common type of leukemia is chronic lymphocytic leukemia, a cancer of mature B lymphocytes. It often has an indolent course and can be found incidentally on a routine blood count showing lymphocytosis, sometimes with mild anemia or thrombocytopenia. A classic clue on the peripheral smear is the presence of smudge cells. Because it tends to affect people over 60 and progresses slowly, many patients are managed with observation rather than immediate therapy. When treatment is needed, options include chemoimmunotherapy or targeted agents, and prognosis varies with stage. This type is more common in the elderly than the acute leukemias (AML, ALL) or even chronic myeloid leukemia, which are less frequent in this age group.