Leukemia is a type of bone marrow cancer.
Bone marrow . Bone marrow transplants can be conducted to treat severe diseases of the bone marrow , including certain forms of cancer such as leukemia . Leukemia , also spelled leukaemia , is a group of cancers that usually begin in the bone marrow and result in high numbers of abnormal white blood cells . Leukemias and lymphomas both belong to a broader group of tumors that affect the blood , bone marrow , and lymphoid system , known as tumors of the hematopoietic and lymphoid tissues . It is the most common type of cancer in children , with three quarters of leukemia cases in children being the acute lymphoblastic type .