Various symptoms indicate chronic myelogenous leukemia (CML) has progressed from one phase to another. These include an increase in leukemia cells, a change in a person’s platelet count, and worsening anemia.

Unlike other cancers, leukemia does not form solid tumors in the body, as it is a blood cancer. CML begins in tissue in the bone marrow that forms blood, which means it can travel and spread wherever blood travels.

This article examines the signs that CML is progressing, the phases of CML, factors that help predict survival, and the outlook.

Worsening symptoms can indicate that CML is progressing.

Symptoms

The symptoms of CML are typically vague, and people sometimes do not recognize them as signs of the disease.

They may include:

CML also causes changes in the blood, as leukemia cells replace the cells in the bone marrow that typically produce blood. Because of this, people with the condition cannot produce enough properly-functioning white blood cells, platelets, and red blood cells.

This can lead to:

Advanced symptoms

As CML progresses, certain symptoms may develop or worsen and can include:

  • lack of appetite
  • fever
  • weight loss
  • bone pain
  • bone damage
  • worsening of anemia
  • increase in leukemia cells
  • enlarged spleen
  • a change in platelet count
  • recurring infections

There are three phases of CML: chronic, advanced, and blast.

Chronic phase

Doctors usually diagnose CML in the chronic phase.

In this phase, people typically have mild or no symptoms. Their bone marrow and blood samples usually have less than 10% blasts, which are atypical, immature white blood cells.

Typically, people whose CML is in the chronic phase respond well to standard treatments.

Accelerated phase

People whose CML is in the accelerated phase may have symptoms such as weight loss, fever, worsening of anemia, and appetite loss. According to the American Cancer Society (ACS), doctors categorize CML as accelerated when:

  • blasts and promyelocytes, another type of immature white blood cell, make up 30% or more of the blood
  • the blood samples contain 15% or more blasts but fewer than 30%
  • a type of white blood cell called basophils makes up 20% or more of the blood
  • there are new chromosome changes in the leukemia cells with the Philadelphia chromosome
  • there is a very low platelet count, which the treatment did not cause

Blast phase

People in this phase typically experience fatigue, shortness of breath, bone pain, infections, and bleeding.

Doctors also refer to the blast phase as the acute or blast crisis phase. In this phase, a person’s blood or bone marrow samples have 20% or more blasts. Large clusters of blasts are visible in the bone marrow, and the blast cells have spread to organs and tissues beyond the bone marrow.

As well as phases, various factors help doctors predict a person’s outlook for survival and plan their treatment.

Doctors associate certain factors with shorter survival times. These adverse prognostic factors include:

  • age, as people aged 60 or older have a less favorable outlook
  • the phase of CML, as doctors associate the accelerated and blast phases with a more unfavorable outlook
  • enlarged spleen
  • a high number of white blood cells called eosinophils and basophils
  • very high or low platelet counts
  • many chromosome changes in CML cells
  • a high number of blasts

As highly effective drugs for treating CML only became available in 2001, there is not enough accurate data showing how they may affect survival. However, according to the ACS, most patients receiving treatment with these drugs are still alive.

One study found that around 90% of people with CML who received treatment with imatinib were still alive within 5 years of starting treatment, and many had typical blood cells.

There are three phases of CML: chronic, accelerated, and blast. Doctors most often diagnose the condition in the first phase. Without treatment, CML will progress to the next phase.

People often have vague, mild, or no symptoms in the chronic phase of CML. They can develop more severe symptoms as the cancer progresses, such as bone pain, frequent infection, and easy bruising and bleeding.

In later phases of CML, blood and bone marrow may contain more blasts and very high or low platelet counts. They could also show chromosome changes.

Various factors besides the phase of CML may also affect prognosis. These include a person’s age and whether they have an enlarged spleen.

Due to the relatively recent introduction of highly effective drugs to treat CML, there is insufficient reliable information on the survival rates of the cancer. However, studies show that most people receiving treatment with these drugs survive for at least 5 years after their initial diagnosis.