It accounted for about 1,500 of the 2,300 cases of childhood leukemia last year. White blood cells called lymphocytes normally protect against viral infections, fight certain cancers, and produce antibodies. But when rapidly producing immature cancerous lymphocytes crowd out normal lymphocytes in the bone marrow, those protective functions are lost. But the disease often returns. Half of all children receiving treatment show no signs of the disease five years later.
Adults fare less well.
There were about 6,000 new cases last year. Unlike AML, in CML some myelocytes mature into functioning granulocytes. But cancerous granulocytes slowly crowd out functioning versions. Blast crisis may also occur where only immature non-functioning granulocytes are suddenly produced, and secondary tumors rapidly appear. Treatment for AML and CML are similar.