The goal of ET treatment is to reduce the risk of complications. But treatment is a balancing act: patients and haematologists must work together to judge whether the benefits of treatment outweight with the downsides, which include not just significant side effects but the potential risks of long-term treatment.

ET patients are at risk of thrombotic (clotting) or haemorrhagic (bleeding) events, so the first goal of treatment is to reduce the likelihood of these events. Haematologists can use a number of different drugs or ‘agents’ to treat ET. These include:

Medications to reduce clotting:

Aspirin is used frequently in ET to prevent clotting and over-active platelets. Aspirin does not reduce the platelet count but can provide protection against thrombotic (clotting) events. It's generally a safe and proven drug, but has some side effects - it can cause bleeding and ulcers in the stomach and digestive system.

If your platelet count is more than 1500 million per ml, there is a risk of haemorrhage, so aspirin is used with caution or not at all. Sometimes drugs similar to aspirin such as dypyrimadole and clopidogrel can be used as alternatives.

Patients can be treated with warfarin, a blood-thinning agent, if they have recently had a venous blood clot or have had multiple clots.

Treatments that reduce the platelet count:

These medications can reduce the incidence of thrombotic complications in high-risk patients. They are called ‘cytoreductive’ drugs because they reduce the amount of blood cells produced by the bone marrow. The decision to use cytoreductive treatments depends on you and your haematologist. You must decide if the risks of using these treatments are outweighed by their benefit. You and your doctor can continue to discuss and review your decision over time.

Therapies to reduce the platelet count include:

Hydroxycarbamide: This drug interferes with cell metabolism and can reduce platelet counts. It is a daily treatment, given in capsule form. Patients taking this drug will need their blood counts monitored every two to three months. Side effects include some darkening of skin, mouth and leg ulcers, and sometimes stomach problems. Hydroxyurea can damage cells and may affect fertility. Women who are pregnant or those trying to conceive should not tale hydroxycarbamide. There is a small chance that this drug may increase the risk of acute leukaemia after 10-15 years of treatment.

Interferon Alpha: This is a natural agent that reduces the production of bone marrow cells. It is used in some ET patients wanting to preserve fertility and can be given to pregnant women. It is given by injection three times a week. The side effects are mainly flu-like symptoms, hair loss, depression, liver and thyroid changes. Evidence suggests that this drug probably does not increase the risk of leukaemia.

Anagrelide: Anagrelide is a drug that lowers the platelet count by reducing the size of the platelet-producing cells. It also should not affect fertility or increase the risk of developing acute leukaemia. Anagrelide can have side effects including headache, palpitations and fluid retention. It is not suitable for pregnancy. It is used with caution in heart disease. In Europe, anagrelide is only licensed as a second line treatment for ET. A recent study called the PT.1 trial suggests that anagrelide may not be as beneficial as hydroxycarbamide in preventing clotting and bleeding complications. It also appears that anagrelide does not prevent transformation to myelofibrosis as well as hydroxycarbamide.

Melphalan, busulphan and phosphorous: Melphalan, busulphan or radioactive phosphorous were the main therapies used to treat ET in the past. However, these drugs can damage bone marrow and make patients infertile. These treatments also increase the risk of acute leukaemia. Haematologists still use busulphan and phosphorous to treat ET in certain cases: when their are side effects from other drugs, when these drugs are not working, or when it is difficult to take the hydroxycarbamide tablets.

Plateletpheresis: This is a treatment that involves the removal of platelets.  A patient's blood is taken into a machine that removes platelets; the blood is then returned to the patient. The aim is to achieve a rapid, temporary control of the platelet count when there are life-threatening complications, or when the platelet count needs a very rapid reduction.

More on treatments: If you'd like to read more about treatments, both conventional and alternative, please click here to go to the Treatments main page

Next: Complications of ET