Chronic myelomonocytic leukemia (CMML) is a condition in which the body creates an excessive number of immature white blood cells, known as myeloblasts and myelocytes. These cells prevent the formation of monocytes, which fight infection and help other blood cells in the body to implement immunity. The extra cells also wreak havoc on the body by taking up needed space in the bone marrow for platelets and red blood cells. As a result, a patient may suffer from various problems, such as anemia, infection, or the tendency to bleed easily.
The condition is more common among older men. It is most commonly caused by environmental elements, chemicals, and radiation exposure. Some cases of chronic myelomonocytic leukemia are also attributed to the use of some types of anticancer drugs. The severity of the condition depends on the number of immature blood cells, or blasts, in the bone marrow or blood while; chromosome changes; how many platelets or white blood cells are in the bone marrow and blood; and if the patient has anemia.
There are two main types of CML, distinguished by the percentage of blasts in the bone marrow and blood, type CMML-1 and CMML-2. The CMML-1 type indicates that there are less than 10 percent of blasts present in the bone marrow and five percent that exist in the blood. The CMML-2 type generally ranges from 10 to 19 percent bone marrow blasts and 5 to 19 percent blood blasts.
Symptoms of CML include anemia, a feeling of fullness below the ribs, and an enlarged spleen or liver. Some patients may develop leukopenia, an infection caused by a low white blood cell count. Other signs of CMML include bruising and bleeding caused by low platelet counts and spots of blood coming from the skin known as petechiae.
Chronic myelomonocytic leukemia is usually not curable. It can be treated with medications such as cytarbine, decitabine, and imatinib, depending on the nature of the condition. If a suitable donor can be found, a stem cell transplant can sometimes cure CMML, particularly in juvenile patients.
The average patient diagnosed with CML is expected to live one to two years after treatment begins. Some factors work against a patient's survival rate, including a large spleen, severe anemia, and a high level of lactate dehydrogenase (LDH). Survival is also less likely for patients who have a large number of blasts or who have an abnormally high white blood cell count in general. In some patients who are not cured, CMML may develop into acute myelogenous leukemia (AML).