Chronic Myelogenous Leukemia - Symptoms, Diagnosis, and Treatment

What Is Chronic Myelogenous Leukemia?

Chronic myelogenous leukemia, or chronic myeloid leukemia, is a type of cancer that affects the blood and bone marrow. In CML, the bone marrow produces too many white blood cells, particularly granulocytes, which are a type of white blood cell involved in the body's immune response. This overproduction is caused by a genetic mutation known as the Philadelphia chromosome, which results from a fusion of two genes: the BCR gene on chromosome 22 and the ABL1 gene on chromosome 9.

The Philadelphia chromosome produces an abnormal protein called BCR-ABL tyrosine kinase, which promotes the uncontrolled growth and division of white blood cells. This excessive production of abnormal white blood cells crowds out healthy cells in the bone marrow, leading to symptoms such as fatigue, weakness, weight loss, fever, and an enlarged spleen.

What Are the Risk Factors Associated With CML?

The exact cause of CML is not fully understood, but some known risk factors may increase the chances of developing the disease.

• CML is more common in older adults, with the average age of diagnosis being around 64 years old. However, it can occur at any age.

• CML occurs slightly more often in males than in females.

• While CML is not typically inherited, having a close relative (such as a parent or sibling) with CML may increase the risk slightly.

• High doses of ionizing radiation, such as that received during certain cancer treatments or nuclear accidents, have been linked to an increased risk of developing CML.

• Some studies suggest that exposure to chemicals like benzene and certain pesticides may be associated with CML. The evidence is not conclusive.

What Are the Clinical Features of Chronic Myelogenous Leukemia?

• CML is a slowly progressive disorder.

• It is initially manifested as weakness and loss of body weight.

• Due to hepatosplenomegaly, the patient may experience stomach aches.

• The leukocyte count crosses above 100,000/uL.

• Among the circulating or hematopoietic cells, an increased number of neutrophils and myelocytes are seen in the body. Other cells like basophils and eosinophils are also elevated.

• Around five percent of myeloblasts are seen in peripheral blood.

• Most of the patients suffering from CML have thrombocytopenia (low platelet count).

• The bone marrow cells exhibit hypercellularity with the enlargement of organs, granulocytes, and megakaryocytes.

• Enlargement of organs like the spleen obstructs blood flow, resulting in pain in the upper left side of the stomach.

What Are the Signs and Symptoms of Chronic Myelogenous Leukemia?

The following are the signs and symptoms of CML.

• Weakness.

• Loss of body weight.

• Night sweats.

• Fever.

• Pain in the lower left side of the abdomen.

• The feeling of fullness in the stomach.

How to Distinguish Leukemia From a Normal Infection of the Blood?

Any normal infection in the blood caused by stress, infection, or abnormal proliferation of cells results in an increased number of immune cells like granulocytes. One such identification marker would be the presence of translocation of the Ph chromosome in cancer patients. Another citation is the absence of alkaline phosphatase in the granulocytes, which is otherwise present.

What Are the CML Stages?

The aggressiveness of chronic myelogenous leukemia is referred to as its phase. The doctor will measure the proportion of sick to healthy cells in the blood or bone marrow to identify the phase. A higher proportion of sick cells indicates a more advanced stage of chronic myelogenous leukemia.

The following are the phases of chronic myelogenous leukemia:

• Chronic: The chronic phase is the first phase and responds to treatment the best in most cases.

• Accelerated: The disease grows more aggressive during the accelerated phase, which is a transitional stage.

• Blast: The explosion phase is a harsh, hostile period that poses a hazard to life.

What Are the Tests to Examine Chronic Myelogenous Leukemia?

The following are the tests to evaluate CML conditions. Such as:

• Complete Blood Count: Elevated neutrophils, myelocytes, basophils, and eosinophils are noted.

• Bone Marrow Aspiration Biopsy: A needle is injected into the hipbone or breastbone to collect tissue samples. It is then studied under the microscope for any abnormal cells.

• Cytogenetic Analysis: Such studies are conducted to evaluate the changes in chromosomes like the Ph chromosome and to check for the response to treatment. It is a cytological study of chromosomes, their arrangements, and missing or extra chromosomes.

• FISH (Fluorescence in Situ Hybridization): A test to evaluate the number of chromosomes and genes.

• Reverse Transcription Polymerase Chain Reaction (RT-PCR): Helps to detect DNA replication and activation of certain genes. This helps in cancer detection.

What Are the Available Treatment Options for Chronic Myelogenous Leukemia?

• Primarily, most patients are given palliative care due to the intense pain.

• Gentle chemotherapy is given.

• Bone marrow transplantation is done. 70 percent of patients have responded positively to this treatment; others fail due to mismatched donors or aged patients with other comorbid conditions.

• The recent development of STI-571, an adenosine triphosphate analog, inhibits the subset of tyrosine kinases, including the BCR-ABL fusion protein. This treatment has proven curative in patients with accelerated phases. It gives complete remission within several months. The STI-571 gives less toxicity and a more chemotherapeutic effect. According to Gleevec, there are advancements toward the development of designer drugs that specifically target oncoproteins.

• Donor Lymphocyte Infusion (DLI) - Lymphocytes from the donor are frozen and kept and later injected into the patient in one or more infusions.

• A surgical procedure like splenectomy is done where the spleen is removed.

• Targeted therapy with a tyrosine kinase inhibitor like Imatinib mesylate, Nilotinib, Dasatinib, and Bosutinib is administered.

• Clinical trials for newer treatments are introduced.

How Is the Prognosis for CML Patients?

• The survival rate of chronic myelogenous leukemia without treatment is three years.

• It is a slowly progressive condition, but after an unpredictable time, the patient enters into an accelerated phase where treatment fails. Such cases are observed in more than half of the survivors.

• The patient often experiences anemia, cytogenetic abnormalities, and other blood dyscrasias.

• CML rarely progresses into extensive bone marrow fibrosis.

What Are the Preventive Measures Against CML?

There are no preventive measures for cancer. Early detection can be challenging due to vague symptoms, leading to delayed diagnosis. But one can adopt certain measures for a healthy lifestyle. Such as:

• Eating healthy foods.

• Avoiding carcinogenic items.

• Exercise.

• Quitting any adverse habits if present.

• Avoid exposure to a high dose of radiation.

Conclusion:

New types of treatments are being introduced for chronic myelogenous leukemia. Treatment for CML has side effects. A proper follow-up is always advised. Not everyone with the risk factors will get CML. Early detection and new therapies like tyrosine kinase inhibitors have helped many people with cancer to live longer and healthier lives. Ongoing research on how CML works and better treatment choices give hope for more progress in treating this disease.