WHAT IS LEUKEMIA?
Leukemia is a form of cancer that starts in blood-forming tissue and most commonly the bone marrow. This leads to the over-production of abnormal white blood cells – the part of the immune system which is responsible for defending your body against infection.
Blood cells are formed in bone marrow, which is the spongy tissue found inside the bones. Blood-forming stem cells divide to produce either stem cells or immature cells that become mature blood cells over time. A blood stem cell may become a lymphoid stem cell or a myeloid stem cell.
Leukemia affects white blood cells and can be classified either by the type of white cell affected (lymphatic or myeloid) or by the way the disease progresses (chronic or acute). Acute and chronic do not refer to the seriousness of the disease but by how rapidly it develops.
There are 4 main types of leukemia:
- Acute lymphoblastic leukemia (ALL) develops rapidly and affects lymphocytes
- Chronic lymphocytic leukemia (CLL) develops slowly and affects lymphocytes
- Acute myeloid leukemia (AML) develops rapidly and affects myeloid cells (granulocytes)
- Chronic myeloid leukemia (CML) develops slowly and affects myeloid cells (granulocytes)
In all types of leukemia, the common causes of symptoms are lack of normal blood cells rather than by the presence of abnormal white cells. As the bone marrow becomes full of leukemia cells, it is unable to produce enough normal blood cells required to support good health which leads to:
- Infections – caused by a lack of normal white blood cells
- More severe and longer lasting infections occur more frequently
- Purpura (small bruises in skin), heavy periods, nosebleeds and even bleeding gums
- Bleeding and bruising – caused by a lack of platelets
- Anaemia – due to insufficient number of red blood cells
- Weakness, tiredness, shortness of breath, light-headedness and palpitations
- Fever, malaise (general feeling of illness) and frequent sweats
There are some symptoms that are only seen in certain patients or forms of leukemia. For example, young children with ALL may complain of bone or joint pain and, in some types of AML, the gums may be swollen by leukemia cells present in the tissue.
In lymphoid malignancies, the lymph nodes (glands) may be swollen. In some forms of leukemia the liver or spleen (an organ of the immune system found just under the ribs on the left hand side) may be enlarged.
Occasionally, some patients who have leukemia will not start treatment straight away however, if this is the case they will have regular check-ups. This is known as “watch and wait” or “active monitoring”. This is mainly relevant for patients with CLL. Almost all patients with CML or with acute leukemia will start treatment soon after being diagnosed. In some patients suffering from CLL, treatment will never be required.
Although patients on “active monitoring” do not have to deal with side effects of treatment, watching and waiting can be an incredibly anxious time for everyone involved. If this applies to you it is vitally important that you let your healthcare team know, as they can offer you extra support and reassurance.
Acute leukemia is often curable with standard treatments, whereas chronic leukemia is usually not curable, but treatable. Often patients with chronic leukemia have a positive initial response to the treatment, however the condition will sometimes relapse (occur again). In most cases the leukemia can be treated again, using similar treatments as were used initially.
The main ways in which this disease is treated are:
The word chemotherapy literally means “therapy with chemicals”. Many chemotherapy drugs are also referred to as cytotoxics (cell toxic) due to the fact that they kill cells – especially ones that multiply quickly like cancer cells. Chemotherapy is the main form of treatment for cancer and is usually administered as a combination of drugs (combination chemotherapy).
Each drug acts together to target the cancer in a different way, however they also have different side effects. In many cases a combination may be more effective than a single drug in controlling your disease as the side effects are kept to a minimum. Chemotherapy is usually given in several cycles (or courses) with rest periods in between. Doing this allows the body time to recover from the side effects.
In most cases you don’t need to be admitted to hospital for chemotherapy, rather, the drugs are usually taken at home or given in the hospital’s day treatment center. Depending on the type of chemotherapy being used and your overall health, you may need to be admitted to the ward for a short while.What is important to note is that chemotherapy is a protocol of administering a certain cocktail of drugs based on the unique patient condition and stage of cancer.
Different doctors, with their own individual experiences might prescribe a different dosage, duration, different drugs etc. Hence it is important to find a doctor that has adequate experience and also works in the patient best interest when subscribing to a chemotherapy treatment plan.
Radiotherapy is a method of treating cancer that uses high energy x-rays to both kill the cancer cells and shrink tumours. Radiotherapy is generally regarded as local therapy because it only destroys cancer cells in the treated area.The radiation field refers to the area of the body that is being treated.
Common fields include the mantle field (treating the lymph nodes of the neck, armpit and chest) the upper abdominal field (abdomen and sometimes spleen), the pelvic field (hips and groin) and the spine. ‘Involved Field Radiotherapy’ is the term sometimes used to describe radiotherapy being given to a local area. The area of normal tissue encompassed by the radiotherapy field is kept to the smallest area possible to avoid affecting other healthy tissue.Before you start radiotherapy, the Radiation Oncologist will carefully calculate the correct dose of radiation therapy needed to effectively treat you.
The area or areas of your body that need to be treated will be marked on your skin with tiny ink dots using a special indelible pen.Radiotherapy is usually given in small doses each weekday (Monday to Friday) over a week or more in the radiotherapy department of the hospital. You do not need to be admitted to hospital for this treatment, however if you live further away, closer accommodation may be needed during this time. Social workers or nurses will be able to assist you with this.When you are having radiotherapy you usually lie on a table underneath the radiotherapy machine, which delivers your calculated dose of radiation.
If necessary, important structures like your heart and lungs are shielded (as much as possible) to ensure that they are not affected by radiation. Radiotherapy is a painless procedure. In fact you do not see or feel anything during the actual treatment, however you will be required to stay perfectly still for the duration of a treatment, which only lasts a few minutes. You can bring along some music to help you relax.
Targeted therapies include inhibitors and monoclonal antibodies. When treating leukemia, inhibitors are usually applied. These inhibitors work by impeding the action of specific cells. When an inhibitor blocks or stops specific cells, such as cancer cells, growth and development of the cell is stopped.
Imatinib is a commonly used inhibitor and works by binding to a specific tyrosine kinase, called bcr-ABL, found on the surface of cells which are Philadelphia chromosome positive (Ph+). These cells are found in people with Chronic Myeloid Leukemia (CML), and in some forms of Acute Lymphoblastic Leukemia (ALL).
This treatment can be taken at home orally and in the form of a tablet or capsule.Newer inhibitors are being developed, not only in the treatment of CML, but across a wide range of cancers. Often they are the sole treatment agent (in the case of CML), but may be given as maintenance such as in the case of ALL. Side-effects experienced are usually mild and reduce over time. These symptoms may include fatigue, skin reactions, mild gastric upsets and fluid retention.
STEM CELL TRANSPLANT
A stem cell transplant is another option that restores healthy bone marrow in patients with leukemia. The purpose of these stem cells is to help stimulate new bone marrow growth and restore the immune system.Before having a stem cell transplant for leukemia, you will undergo an intensive conditioning regimen, which involves destroying as many leukemia cells as possible. You may receive high doses of chemotherapy and even radiation therapy. You may also receive reduced-intensity conditioning (a “mini-allogeneic transplant”), which uses lower, less toxic doses of chemotherapy and/or total body irradiation (TBI) before the transplant.Once this preparative regimen is complete, you will be ready to undergo the transplant.
This procedure is much like a blood transfusion, as you’ll receive the stem cells intravenously. After entering the bloodstream, the stem cells travel to the bone marrow and start to make new blood cells in a process known as engraftment. The procedure takes about an hour in total.In the months following the transplant, your care team will monitor your blood counts as it is possible you may need transfusions of red blood cells and platelets.
Sometimes, the intensive treatments you receive before the stem cell transplantation for leukemia can cause side effects such as infection. If this happens, your doctor may administer IV antibiotics.If you had an allogeneic stem cell transplant, your doctor may prescribe you certain drugs to reduce the risk of graft-versus-host-disease (GVHD) – a condition where the donated cells attack the patient’s tissues.
Although a doctor may suspect a patient has leukemia based on a number of signs and symptoms, it can only be diagnosed using laboratory tests.
- Physical exam: During a physical exam, your doctor will look for any physical signs of leukemia, such as pale skin from anemia, swelling of your lymph nodes, and enlargement of your liver and spleen.
- Blood tests: The results of a simple blood count will usually indicate whether you have leukemia, although very rarely, a blood count may come back as being normal.
- Bone marrow test: Your doctor may recommend you have a procedure to remove a sample of bone marrow from your hipbone. The bone marrow is removed using a long, thin needle. The bone marrow sample is then sent to a laboratory to look for leukemia cells. Specialized tests of your leukemia cells may reveal certain characteristics that are used to determine what treatment options are suitable for you.