How is MPN treated?
Polycythaemia vera (PV)
The goal of treatment for PV is to reduce the number of cells in your blood and help you to maintain a normal blood count. This helps control any symptoms of your disease and reduces the risk of complications due to blood clotting, or bleeding. The treatment or combination of treatments chosen for you will depend on several factors including the duration and severity of your disorder, whether or not you have a history of blood clots, your age and your general health. In addition to treatment, your doctor will advise you on ways to stay healthy and reduce any lifestyle factors that might increase your risk of thrombosis. For example you may be advised to stop smoking, and/or take a series of steps to maintain a healthy weight range and blood pressure. Your doctor or nurse will explain any side effects you might experience while you are having these treatments and how they can be managed.
Venesection (or phlebotomy) is a procedure in which a controlled amount of blood is removed from your bloodstream. This procedure is commonly used when people are first diagnosed with PV because it can help to rapidly reduce a high red cell count. It is a process similar to a blood donation. This is usually done in the outpatient’s department of the hospital. This procedure may need to be repeated frequently at first, usually every few days, until your blood count is reduced to the desired level.After this, you may need to have the procedure repeated periodically. For many people, particularly younger patients and those with mild disease, regular venesection (every few months) may be all that is needed to control their disease for many years.
These drugs are commonly used for people with an extremely high platelet count, complications due to blood clotting or bleeding, or symptoms of an enlarged spleen or for some people who are unable to tolerate venesection. The most commonly used myelosuppressive agent is an oral capsule chemotherapy drug called hydroxyurea. It is particularly useful in controlling a high platelet count and therefore reducing the risk of thrombosis. Another less commonly used chemotherapy drug is busulfan. This drug is also given in tablet form. Chemotherapy taken in capsule form is tolerated well by most people and side effects tend to be few and mild.
Interferon is a substance produced naturally by the body’s immune system. It plays an important role in fighting disease. In PV, interferon is sometimes prescribed for younger patients to help control the production of blood cells. Interferon is usually given as an injection under the skin (subcutaneous injection) using a very small needle. You or a family member (or friend) will be taught how to do this at home. The main side effects are flu-like symptoms such as chills, fevers, aches and pains and weakness.
Many people are prescribed small daily doses of aspirin, which have been shown to significantly reduce the risk of thrombosis in people with PV. Aspirin works by preventing your platelets from clumping together to form harmful blood clots in different parts of your body.
Anagrelide hydrochloride (Agrylin) is a drug used to reduce high platelet counts in people with PV and essential thrombocythaemia. Anagrelide affects platelet-producing cells in the bone marrow called megakaryocytes, slowing down platelet production and therefore reducing the number of platelets in the circulating blood. Anagrelide is taken in capsule form by mouth. The most commonly reported side effects include headaches, fast or forceful heart beat (palpitations), diarrhoea, weakness, fluid retention, nausea, dizziness, abdominal pain and shortness of breath. You should report any side effects you are experiencing to your doctor. You need to contact your doctor immediately if you experience the following symptoms: shortness of breath or difficulty breathing, swollen ankles, fast or irregular heartbeat, and/or chest pain. You should not stop taking this or any other medication for PV unless instructed by your doctor. Stopping these medications suddenly can be harmful.
Essential thrombocythaemia (ET)
The goal of treatment for people with ET is to prevent complications like abnormal bleeding and bruising and in some cases reducing the number of platelets in the blood. You may not have any symptoms of ET when you are first diagnosed and therefore may not require any treatment for some time. Instead your doctor may recommend a ‘watch and wait’ strategy which involves regular check-ups and blood counts to carefully monitor your health. In addition they will advise you on the steps you can take to stay healthy and reduce any lifestyle-related risk factors you may have that increase your chances of developing a blood clot. You may be advised, for example, on ways to help you stop smoking and maintain a healthy weight range and blood pressure.
For people at high risk of thrombosis, a chemotherapy drug called hydroxyurea with or without low-dose aspirin is often used as a first-line treatment. Hydroxyurea works by suppressing the function of your bone marrow and thereby controlling platelet production, while aspirin prevents your platelets from aggregating and forming harmful clots in your body.
Anagrelide hydrochloride and Interferon
Anagrelide hydrochloride (Agrylin) and interferon may also be used. Interferon works by suppressing the abnormal megakaryocyte clone in your bone marrow thereby reducing the overproduction of platelets. Those at low risk may be simply treated using low-dose aspirin or an equivalent drug alone. They usually have a very good outlook with no difference to the general population.
Some people have no symptoms when they are first diagnosed with myelofibrosis and do not require treatment straight away, apart from regular check-ups with their doctor to carefully monitor their disease. For others treatment is largely supportive and is aimed at preventing complications due to low blood counts and an enlarged spleen. This may include periodic blood transfusions and taking antibiotics to prevent and treat any infections. A chemotherapy drug such as hydroxyurea, or low-doses of a drug called thalidomide may be used to reduce an enlarged spleen. In some cases, the surgical removal of the spleen (splenectomy) may be considered. Small doses of radiation to the spleen can also be given to reduce its size. This usually provides temporary relief for about three to six months.
Some younger patients who have a suitably matched donor may be offered an allogeneic (donor) stem cell transplant. This is a medical procedure that offers the only chance of cure or long-term survival in patients with myelofibrosis. Stem cell transplants carry significant risks and are only suitable for a small minority of younger patients (usually under 60 years).
JAK2 inhibitors work by blocking the activity of the JAK2 protein, which may lead to a reduction in splenomegaly and decreased symptoms. They also work in patients with myelofibrosis without the JAK2 mutation. Side effects may include worsening anaemia or a low platelet count. Ruxolitinib is the only JAK2 inhibitor currently licenced for use in Australia. A number of JAK2 inhibitors may be available in clinical trials or may become available in the near future.
Side effects of treatment
All treatments can cause side effects. However, the type and severity will vary between individuals, depending on the type of treatment used and how an individual responds to it. In general, more intensive treatment is associated with more severe side effects. It is important to report any symptoms you are having to your doctor or nurse. In most cases they can be treated and are reversible.
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