Chronic myeloid leukaemia

CML stands for chronic myeloid leukaemia, and it is a type of slow blood cancer. This cancer starts in the blood-forming cells of the bone marrow and invades the blood. In CML, leukaemia cells tend to build up in the body over time, but in many cases people don’t have any symptoms for at least a few years. With time, these cells invade other parts of the body, including the spleen. CML can also change into a fast-growing form known as acute leukaemia which is capable of invading any organ in the body. Most people with CML have Philadelphia chromosome – a gene mutation wherein chromosome 9 and chromosome 22 are interchanged.

Chronic Myeloid Leukaemia (CML) is the most common adult leukaemia in India that affects people between the age groups of 30 and 60. It is more common in males than in females with almost 0.8 to 2.2 males out of 100,000 being diagnosed every year. With these startling statistics, it is about time people woke up to the possibility of contracting this disease. Dr Shyam Agarwal, senior consultant at Sir Ganga Ram Hospital, New Delhi, tells us more about the most common form of blood cancer in adults.

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Causes

The exact cause of CML is not known, but the patient usually comes to us with symptoms like -


  • An enlarged spleen

  • Left-sided abdominal pain

  • Weakness

  • Low grade fever

  • Loss of appetite

  • Loss of weight


On further testing we find their white blood cell count or total lymphocyte count is raised to a great extent, which is one of the hallmarks of this condition. On further testing we find what is called the ‘Philadelphia chromosome’. Here, chromosome 9 and chromosome 22 are interchanged, because of which, the person’s genes don’t function properly. This leads to the rearrangement of two genes known as BCR and Abl1 gene. Because of this rearrangement the white blood cells within the patient’s bone marrow begins to reproduce abnormally leading to the manifestation of symptoms.

Read more about causes, symptoms, diagnosis and treatment of blood cancer.

Symptoms

One of the most common symptoms is the enlargement of the spleen, low-grade fever and weakness. Bruising as seen in other forms of this disease can happen in about as low as 10 people in the whole population. One will most commonly find bruising in people suffering from acute leukaemia and not this form of the disease.

These are the hallmarks. One should visit a doctor immediately if they see these symptoms. 

Diagnosis

Dr Shyam Agarwal says,The earlier the condition is diagnosed, the better the treatment.  In this disease there is a scoring system in which the burden of the disease is estimated. But like I said this condition is due to gene rearrangement, so if we control or block this malfunction then most patients suffering from CML recover, even if it is diagnosed a bit late. ‘

A blood test shows very high white blood cell count. The test can identify the presence of the faulty genes, but to get a proper diagnosis a bone marrow biopsy is necessary.

We usually take a bone marrow aspiration to identify the presence of the Philadelphia chromosome in the bone marrow and confirm the presence of the rearranged BCR gene and Able1 gene by the FISH method (Fluorescence in-situ hybridization) or PCR method (polymerase chain reaction).

Treatment

The goal of chronic myelogenous leukaemia treatment is to eliminate the blood cells that contain the abnormal BCR-ABL gene.

Drugs: Targeted therapy with Imatinib, Nilotinib or Dasatinib is initiated as soon as the cancer has been diagnosed. These medicines slow the progression of cancer. The tablets need to be taken every day for life. There are two more drugs that have been introduced, but they are not currently available in India. They are Ponotanib and Bosutinib.

The good thing about medicines is that they are easier for patients to deal with than a treatment like chemotherapy. The patient can eat them at home and there are no serious side effects. They are known as targeted drugs. Patients usually have mild side effects like water retention (oedema), swelling in the face and lightening of the skin. In the case of Dasatinib, which is more potent, patients do suffer from a condition called plural effusion (which is the accumulation of fluids in the lungs), but with proper regulation of their dosage this side effect is also controlled.

In comparison, these are fairly mild side effects and don’t interfere with the patient’s quality of life does. Patients have been eating these medicines for a very long time and leading an absolutely normal life. They get married and can also have children. This is one disease where the medicine acts as a magic bullet. We do prescribe other medication along with this to counter side effects, like diuretics to beat the water retention problem so most don’t have too much trouble. More importantly these drugs are good in the long run.

Chemotherapy : It is usually started if the chronic cancer reaches an advanced stage.

Bone marrow transplant: The drugs that we have today are doing a good job in controlling the condition that is why a bone marrow transplant has become the second line of treatment. This is because a bone marrow transplant is an expensive and cumbersome procedure, costs a lot more than the drugs and only about 60% of the patients treated with this surgery recover. Moreover, about 40% of the patients die due to the bone marrow transplant surgery in about four to six months. So, now that we have medicines that work on the root of the problem, that is to block the misplaced gene’s functions, and heals about 98-99% of the patients, bone marrow transplants are not the norm.

The treatment used to be more expensive earlier. All these medicines are available in about five to ten thousand rupees per month, and they are very readily available. There are also some schemes for poor patients that provide these medicines to them free of cost.

The most important thing for patients is for them to remember that they have to take these medicines as long as they live. They must get regular checkups where we monitor their BCR and Abl1 gene by doing regular blood tests. These patients should remember that they should not discontinue the medicines even after their blood reports become normal.

Complications

CML has three phases, the first one is the chronic phase which goes on for about three to three-and-a-half years, after that the disease progresses more swiftly, and this phase is known as the accelerated phase.

In this phase the patient’s haemoglobin level drops, he/she has an extremely swollen spleen and one can see increased levels of basophils and blasts (types of blood cells) in the person’s blood and bone marrow. These numbers increase markedly, and this phase lasts about six to eight months.

After this, if the patient does not get treated they get into the blast phase which is also known as acute leukaemia. This is the last phase and is extremely short and the patient usually dies in about two to three days. This phase is untreatable and the most severe part of the disease.

 

The content has been verified by Dr Shyam Agarwal, senior consultant at Sir Ganga Ram Hospital, New Delhi.

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