Those with symptoms of leukemia or Chronic Myelogenous Leukemia (CML) are further investigated to confirm the diagnosis of CML and commence treatment.
The diagnosis is made by a haematologist or a haemato-oncologist – one who specializes in cancers and disorders of the blood.
A routine blood smear examination as well as blood count evaluation often gives clues to leukemias in general.
The complete blood count (CBC) is a test that measures the levels of different blood cells such as red blood cells, white blood cells, and platelets. Suspected cases of CML are usually first detected after a blood test.
The blood tests reveal abnormally high levels of white blood cells and high blast cell or immature white blood cell count in blood.
Blood biochemistry tests help to determine the liver and kidney functioning and determine the levels of certain minerals and enzymes present in blood.
Bone marrow biopsy
A small sample of bone marrow is taken. This is called bone marrow biopsy.
The bone marrow biopsy is performed under local anesthesia. The physician will numb an area of skin at the back of the hip bone and use a wide bore needle to remove the bone marrow sample.
There may be a little pain and bruising after the procedure. The procedure takes around 15 minutes to complete and may be performed on an outpatient basis.
The bone marrow sample is then smeared onto a glass slide and examined under the microscope. Cancer cells if detected may offer clues as to the type of leukemia – lymphoid (CLL) or myeloid (CML).
This is a highly specific test that assess the genetic makeup of the cancer cells. The leukemia is caused by severe distinctive DNA mutations.
Some of these are specific for the patient to respond to specific modalities of treatment. Thus cytogenetic testing is important for determining the modality of treatment and drugs to be used for optimum benefit.
For example, 90% of people with chronic myeloid leukaemia have the Philadelphia chromosome. People who have this chromosome are known to respond well to a medicine that belongs to the group tyrosine kinase inhibitors called Imatinib. Some of the tests used for cytogenetic evaluation include PCR and FISH.
These include X rays, CT scans and MRI scans. CT (computed tomography) scans. These are not diagnostic tests that can confirm presence of CML but may provide clues as to the extent of spread of the cancer to other organs.
MRI scans are mainly useful to check for spread to the brain and spinal cord. Ultrasound examinations may be used to check for abnormal growths in the abdomen.
Staging of CML
Once the diagnosis of a cancer is confirmed, it is staged into stages of the disease progression. Staging helps in planning treatment and predicting the outcome of a cancer.
Most types of cancer are staged based on the size of the tumor and how far it has spread from the origin of the cancer. This system is not useful in leukemias as there are no solid tumours in this case.
For CML there are phases of development of the disease. CML is divided into 3 groups that help predict outcome of the cancer. These phases are classified based on the number of immature white blood cells or blast cells seen in the blood or bone marrow. The phases are:-
In this phase there are less than 10% blast cells in blood. Patients usually have mild symptoms and are responsive to standard treatment. Most patients are diagnosed in the chronic phase
In this phase there are more than 10% and less than 20% blast cells in blood or bone marrow. In this phase there are symptoms of fever, weight loss and poor appetite. The response to usual drug treatment is poorer than chronic phase.
This phase is also called acute phase or blast crisis. In this phase there are over 20% blast cells in blood or bone marrow. At this point the CML acts like acute leukemia because of its aggressiveness and rapid growth.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)