Twenty percent of CMML-1 patients and 10 percent of CMML-2 patients survive five years or more from diagnosis, with median survival rates of 20 months and 15 months respectively, according to the American Cancer Society. Patients with CMML-2 are more likely to develop acute myeloid leukemia, a fast developing cancer.
Doctors stage chronic myelomonocytic leukemia, a blood marrow disease, by the percentage of blasts, or abnormal immature blood cells, among the white blood cells and blood marrow, explains the American Cancer Society. In CMML-1, 5 percent or less of white blood cells and 10 percent or less of the cells in the bone marrow cells consist of blasts. In CMML-2, between 5 and 20 percent or less of white blood cells and between 10 and 20 percent of bone marrow cells consist of blasts.