Chronic myeloid leukaemia (CML) is a type of cancer that affects the white blood cells. “Chronic” means that the condition progresses slowly over a period of years, and “myeloid” refers to the type of white blood cells that are affected. Leukaemia itself is characterized by the overproduction of abnormal white blood cells, which can lead to various complications.
Types of Chronic Leukaemia
Chronic leukaemia is classified based on which type of white blood cells are involved:
- Lymphocytes – primarily fight viral infections.
- Myeloid cells – play multiple roles, including fighting bacterial infections, defending against parasites, and controlling tissue damage.
CML specifically involves cancerous changes in the myeloid cells. Other types of leukaemia include:
- Chronic lymphocytic leukaemia (CLL)
- Acute myeloid leukaemia (AML)
- Acute lymphoblastic leukaemia (ALL)
What Happens in Chronic Leukaemia
The bone marrow, a spongy tissue within bones, produces stem cells that can develop into three essential blood cell types:
- Red blood cells (RBCs) – carry oxygen throughout the body.
- White blood cells (WBCs) – fight infections.
- Platelets – help control bleeding.
In CML, a genetic mutation in stem cells leads to an overproduction of white blood cells. This overproduction reduces the number of red blood cells and platelets, resulting in symptoms such as:
- Anaemia (due to a lack of red blood cells), which can cause tiredness.
- Increased bleeding risk (due to a lack of platelets).
Warning Signs of Chronic Myeloid Leukaemia
Early-stage CML often does not produce noticeable symptoms. As the condition progresses, the following symptoms may develop:
- Tiredness or fatigue
- Unexplained weight loss
- Night sweats
- A feeling of bloating or fullness (due to an enlarged spleen)
- Bruising easily
- Bone or joint pain
How Common Is Chronic Myeloid Leukaemia?
CML is a rare form of cancer and can occur at any age, although it is more frequently seen in people aged 40 to 60. Unlike some other cancers, there is no evidence that CML runs in families.
If you have concerns about symptoms or would like more information about CML, speak with your healthcare provider, who can offer diagnosis, guidance, and support tailored to your needs.
Symptoms of Chronic Myeloid Leukaemia (CML)
Early Stages: In its early stages, chronic myeloid leukaemia (CML) often does not cause noticeable symptoms and is frequently diagnosed during routine blood tests or examinations conducted for unrelated conditions. When symptoms do develop, they may resemble those of various other illnesses and can include:
- Tiredness: Feeling fatigued without a clear cause.
- Frequent Infections: Increased susceptibility to infections due to abnormal white blood cells.
- Unexplained Weight Loss: Losing weight unexpectedly without a change in diet or activity level.
- Feeling of Bloating: A sensation of fullness or bloating, often related to an enlarged spleen.
- Swollen Lymph Nodes: Occasionally, painless swelling of lymph nodes located in the neck or under the arms.
Spleen Involvement: Chronic myeloid leukaemia can lead to an enlarged spleen (splenomegaly), a condition that may cause:
- Abdominal Lump: A lump on the left side of the abdomen that can be tender to the touch.
- Pressure on the Stomach: This may lead to a reduced appetite and symptoms of indigestion.
Advanced Stage Symptoms: As chronic myeloid leukaemia progresses, symptoms can become more severe and noticeable. These include:
- Severe Fatigue: A marked increase in tiredness that interferes with daily life.
- Bone Pain: Persistent or worsening pain in bones.
- Night Sweats: Profuse sweating during the night that may soak bedding.
- Fever: Unexplained fever without any apparent cause.
- Easy Bruising or Bleeding: Skin may bruise more easily, and there may be frequent or prolonged bleeding due to reduced platelet counts.
Note: If you or someone you know is experiencing these symptoms, it’s important to seek medical attention to determine the underlying cause and receive appropriate care.
Causes of Chronic Myeloid Leukaemia (CML)
Genetic Mutation in Stem Cells: Chronic myeloid leukaemia (CML) is caused by a genetic mutation in the stem cells responsible for producing white blood cells. This mutation leads to the overproduction of white blood cells, which are often released into the bloodstream before they mature into fully functional infection-fighting cells. As these immature cells accumulate, the production of healthy red blood cells and platelets decreases, causing many symptoms of chronic leukaemia.
The Philadelphia Chromosome:
- Nature of the Mutation: Most individuals with CML have a specific genetic abnormality known as the Philadelphia chromosome. This occurs when a section of DNA from one chromosome swaps places with a section from another chromosome.
- Protein Production: The Philadelphia chromosome causes cells to produce a protein that promotes the rapid growth and resistance to normal cell death of leukaemic cells. This leads to the uncontrolled multiplication of abnormal cells.
Genetic Cause but Not Inherited:
- The genetic abnormality responsible for CML is not inherited but acquired during a person’s lifetime.
Possible Triggers for CML:
- Radiation Exposure: The only proven risk factor for chronic myeloid leukaemia is exposure to extremely high levels of radiation, such as after nuclear accidents or atomic bomb explosions.
- Benzene Exposure: Prolonged exposure to benzene, a chemical found in petrol and used in the rubber industry, may slightly increase the risk of CML. Benzene exposure is strictly controlled in many countries, including the UK, to minimize risk. Smoking, which contains benzene, is more commonly associated with acute rather than chronic leukaemia.
- Occupational Risks: Certain occupations have been linked to an increased risk of CML due to possible exposure to chemicals or pesticides. These occupations include:
- Agricultural workers
- Rubber or plastic manufacturers
- Tailors and dressmakers
- Cleaners
- Builder’s labourers
Additional Risk Factors:
- Obesity: There is some evidence linking obesity to an increased risk of chronic leukaemia.
- Weakened Immune System: Individuals with a compromised immune system, such as those with HIV/AIDS or those taking immunosuppressants after an organ transplant, may have a higher risk of developing CML.
- Inflammatory Bowel Disease: Conditions such as ulcerative colitis or Crohn’s disease may also be associated with an increased risk of chronic leukaemia.
While certain factors are known to increase the likelihood of developing CML, the precise trigger that initiates the genetic mutation remains unclear in most cases.
Diagnosing Chronic Myeloid Leukaemia (CML)
Initial Detection: Chronic myeloid leukaemia (CML) is often first discovered during routine blood tests conducted for unrelated reasons. Elevated white blood cell levels may indicate the presence of chronic leukaemia. If such abnormalities are detected, you will be referred to a haematologist, a specialist in blood conditions, for further examination.
Bone Marrow Biopsy
To confirm a diagnosis of chronic leukaemia, a haematologist typically performs a bone marrow biopsy, which involves taking a small sample of bone marrow to analyze under a microscope.
- Procedure: The area on the back of your hip bone is numbed with a local anaesthetic. The haematologist uses a needle to extract a sample of bone marrow.
- Experience: You may feel pain once the anaesthetic wears off, and bruising or discomfort may last a few days. The biopsy typically takes around 15 minutes, and you won’t need to stay in the hospital overnight.
- Purpose: The sample is examined for cancerous cells and helps determine the specific type of chronic leukaemia present.
Additional Tests
Several tests may be conducted to gain a more comprehensive understanding of the leukaemia’s progression and determine appropriate treatment approaches.
Cytogenetic Testing
- Purpose: This test identifies the genetic composition of cancerous cells. There are several genetic variations that can occur during leukaemia, and identifying them is crucial for determining treatment.
- Example: Around 90% of people with CML have the Philadelphia chromosome, which is known to respond well to the medicine imatinib.
Polymerase Chain Reaction (PCR) Test
- What it Does: This test analyzes a blood sample to help diagnose and monitor the response to treatment.
- Frequency: It is typically repeated every three months for at least two years after starting treatment and less frequently once remission is achieved.
Imaging Tests In certain cases, imaging tests may be performed to rule out other conditions or confirm a diagnosis of CML. These may include:
- X-ray: Often used to examine the chest.
- Ultrasound Scan: Typically used to assess the spleen and liver.
These tests provide essential information to understand the extent of the disease and to tailor the most effective treatment strategy for each individual.
Treating Chronic Myeloid Leukaemia (CML)
Main Treatment Option: Imatinib Tablets
- Initial Treatment: Imatinib tablets are often prescribed as soon as chronic myeloid leukaemia is diagnosed. Taken daily for life, they aim to slow the progression of the disease.
- Treatment Goals:
- By 3 Months: Normalize blood counts.
- By 12 Months: Clear the bone marrow of Philadelphia chromosome-positive cells.
- By 18 Months: Achieve molecular remission, where leukaemia can only be detected using very sensitive tests.
- Side Effects of Imatinib: Generally mild, such as nausea, vomiting, swelling in the face and legs, muscle cramps, rashes, and diarrhoea.
Alternative Treatments for Resistance to Imatinib:
Nilotinib
- Usage: Prescribed if a patient is resistant or intolerant to imatinib. Nilotinib may also be used as a first-line treatment in some cases.
- Function: Similar to imatinib, it blocks proteins that stimulate cancer cell growth.
- Side Effects: Can include vomiting, abdominal pain, bone and joint pain, dry skin, appetite loss, hair loss, insomnia, night sweats, dizziness, and tingling or numbness.
Treating Advanced CML
Chemotherapy
- Oral Chemotherapy: Typically used first due to milder side effects like tiredness, skin rash, and increased infection risk.
- Intravenous Chemotherapy: Used if oral chemotherapy is ineffective. It tends to cause more severe side effects such as nausea, vomiting, tiredness, hair loss, and potential infertility.
Bone Marrow and Stem Cell Transplants
- Potential Cure: This treatment is generally considered only for select cases, typically for younger or healthier patients.
- Procedure: Involves high-dose chemotherapy and radiotherapy to eliminate cancer cells before receiving donor bone marrow.
- Donor Matching: Best outcomes occur when the donor is a matched sibling.
- Risks: The aggressive nature of the treatment poses significant risks and potential complications, often outweighing the benefits for many patients. However, individual circumstances may indicate a favorable benefit-risk balance.
Complications of Chronic Myeloid Leukaemia (CML)
1. Weakened Immune System (Being Immunocompromised)
- Causes:
- Lack of Healthy White Blood Cells: This reduces the body’s ability to fight infections.
- Medications for Chronic Leukaemia: Many treatments can further weaken the immune system.
- Increased Risk of Infections: People with CML are more vulnerable to infections, and these infections can become more severe and lead to complications.
- Preventive Measures:
- Antibiotics: You may be advised to take regular doses of antibiotics to prevent infections.
- Immediate Reporting of Symptoms: Prompt treatment is essential to prevent severe complications. Watch for:
- High temperature (fever) of 38°C (101.4°F) or above
- Headache
- Aching muscles
- Diarrhoea
- Tiredness
- Avoiding Infection Exposure: Avoid contact with anyone who has an infection, including conditions like chickenpox or measles, even if you were previously immune.
- Minimizing Public Exposure: Limit trips to crowded places and avoid public transport during rush hour.
- Vaccinations: Make sure your vaccinations are up-to-date, but avoid vaccines with activated virus or bacterial particles (e.g., MMR, polio, oral typhoid, BCG, yellow fever). Your GP or care team will provide guidance.
2. Psychological Effects of Chronic Leukaemia
- Emotional Impact: A diagnosis of chronic leukaemia can be very distressing, particularly if the condition is not curable. The stress of waiting to see how the disease progresses can lead to anxiety, depression, and other emotional struggles.
- Managing Psychological Wellbeing:
- Counselling and Psychiatric Support: Talking to a counsellor or psychiatrist can help manage feelings of anxiety and depression.
- Medication: Antidepressants or anti-anxiety medications may be recommended to help cope with emotional challenges.
- Support Groups: Engaging with others who have CML through support groups may provide comfort and shared experiences. Your GP or care team can connect you with local resources.
- Macmillan Cancer Support: An excellent resource for those with leukaemia. Contact their helpline at 0808 808 00 00, open Monday to Friday, 8am to 8pm, for support and guidance.
Further Information: For more comprehensive details, you can explore resources like Cancer Research UK, which provides extensive information about chronic myeloid leukaemia and its management.
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