Polycythemia vera is a rare type of blood cancer which commonly develops slowly and may be undetectable until a blood test is carried out for another reason. The condition is called a ‘myeloproliferative disorder’ which refers to when bone marrow produces blood cells in a rapid and uncontrolled way.When the bone marrow makes too many red blood cells, an excess can thicken the blood which can slow the flow and potentially cause blood clots. The condition is caused by a mutation in a gene during blood cell production. The reason for this mutation is unknown, however it is generally not inherited.

PV can occur at any age, however, is more common between the ages of 50-75; affects men more than women, however women are inclined to get the disease at a younger age. The global incidence in 2020 was estimated to be 2.3-2.8 per 100,000 persons/year, with a median age of approx. 60 years.

Signs and symptoms

Ambiguous or unclear:

• Headache
• Dizziness
• Fatigue
• Blurred vision

More specific:

• Itchiness, particularly after a warm bath or shower.
• Numbness, tingling, burning or weakness in arms, hands, legs or feet.
• Feeling full soon after eating; bloating or pain in left upper abdomen.
• Unusual bleeding – nose bleeds or bleeding gums.
• Painful swelling on one joint; commonly the big toe.
• Shortness of breath; difficulty breathing when lying down.

Complications

As mentioned above, PV can cause other health complications:

Open sores on the inside lining of the stomach, upper small intestines or oesophagus, and inflammation of the joints (gout).

Blood clots – elevated risk is caused by an increase in blood thickness, decrease in blood flow, or abnormalities in platelets.

Enlarged spleen – an increase in the number of blood cells makes the spleen work harder than normal, causing it to become larger.

Iron deficiency – almost all PV patients are iron deficient, either at diagnosis or during the course of the disease.

In rare cases, it can lead to a progressive disorder where bone marrow is replaced with scare tissue, a condition in which stem cells are not able to mature or function properly, or cancer of the blood and bone marrow – acute leukaemia.

Thrombotic events and cardiovascular disease (CVD) are the most common complications in patients with PV compared with other myeloproliferative disorders. It is the major cause of morbidity and mortality in this population group.

This disorder can be life-threatening without proper medical treatment. Therefore, addressing signs, symptoms and complications of the disease is significantly important.

Treatment

The most common therapy for patients with PV is regular blood withdrawals, called phlebotomy (or venesection). Among PV patients with increased severity, this treatment is required often as it is essential to decrease blood volume and an excess of red blood cells, which will also reduce the risk of thromboembolism. However, regular application of this procedure can have an impact on daily life and wellbeing as it may cause iron deficiency and worsen PV-related symptoms.

Perth Blood Institute will be conducting a clinical trial to evaluate the efficacy of sapablursen, a drug to help reduce how often phlebotomies are needed and improve the quality of life in people with PV.

For more information about the clinical trial please visit ISIS 702843.

---

References

• Polycythemia vera - Symptoms and causes - Mayo Clinic
• Polycythemia vera - Diagnosis & treatment - Mayo Clinic
• New Perspectives on Polycythemia Vera: From Diagnosis to Therapy - PMC (nih.gov)
• Phlebotomy Frequency and Quality of Life and Productivity in Patients with Polycythemia Vera: Results from the MPN Landmark Survey in the United States (sciencedirectassets.com)
• Griesshammer, M., Kiladjian, J.J., & Besses, C. Thromboembolic events in polycythemia vera. Ann Hematol. 2019; 98(5):1071-1082. doi: 10.1007/s00277-019-03625-x.