What is the most common leukemia in adults?

Chronic Lymphocytic Leukemia (CLL) is the most common leukemia in adults. This form of leukemia primarily affects older adults, with a median age of diagnosis in the 70s. CLL is characterized by the accumulation of functionally incompetent lymphocytes, particularly B-like cells, in the peripheral blood, bone marrow, and lymphoid tissues. Patients often present asymptomatically or with lymphadenopathy, splenomegaly, or cytopenias, and it typically has a slower progression when compared to other types of leukemia.

In contrast, Acute Myeloid Leukemia (AML) and Acute Lymphoblastic Leukemia (ALL) are more aggressive forms of leukemia but are less prevalent in the adult population as a whole. Chronic Myeloid Leukemia (CML), while also a recognized type in adults, has a lower incidence than CLL. Understanding these distinctions helps clarify why CLL is recognized as the most common leukemia among adults.