Myeloproliferative Neoplasms (MPNs) are a group of blood cancers which affect the bone marrow.1 The three main types of MPNs are:
Myelofibrosis (MF) – which causes scar tissue to build up inside the bone marrow, meaning blood cells can’t be produced effectively, leaving patients with low numbers of red blood cells2
Essential thrombocythaemia (ET) – which results in the blood containing too many platelets, leaving patients at a higher risk of developing blood clots3
Polycythaemia vera (PV) – which causes the overproduction of red blood cells4
MPNs are relatively rare, and most people diagnosed are over the age of 60.2,3,4 MF occurs in around one in every 100,000 people, and around 0.5 – 2 cases of ET or PV are diagnosed per 100,000 people.3,4
MF can develop spontaneously (primary MF), or can develop in people who have ET or PV (secondary or post-ET / post-PV MF).2 MF causes scarring of the bone marrow (fibrosis), which affects its ability to produce healthy blood cells and as a result organs like the liver and spleen compensate and produce blood cells in its place.2
Like MF, ET also affects blood cell development, with patients producing a higher than normal number of platelets.3 The disease develops slowly and does not cause any symptoms during early stages, but those with ET can go on to develop other MPNs. Patients with PV produce too many red blood cells, and can be at an increased risk of blood clots.4
For those diagnosed with MPNs who do not have symptoms, a ‘watch and wait’ approach to treatment is often recommended.5 This involves regular monitoring and check-ups with a haematologist, as well as maintaining a healthy lifestyle. If the symptom burden increases, treatment options are:1 • Bone marrow transplant in eligible patients with higher-risk disease • Cytoreductive therapy (mostly hydroxyurea or interferon) • JAK inhibitors • Supportive therapy (e.g. aspirin, steroids, ESAs, phlebotomy)
Tefferi A, Pardanani A. Myeloproliferative Neoplasms: A Contemporary Review. JAMA Oncology. 2015;1(1).
Harrison C, McLornan D. Myelofibrosis. Hematology. 2014;19(2):120-1
Brière JB. Essential thrombocythaemia. Orphanet Journal of Rare Diseases. 2007;2(3).
Stuart BJ, Viera AJ. Polycythemia Vera. American Family Physician. 2004;69(9):2139-2144.
Hasselbach HC. The platelet–cancer loop in myeloproliferative cancer. Isthrombocythemia an enhancer of cancer invasiveness and metastasisin essential thrombocythemia, polycythemia vera and myelofibrosis? Leukemia Research. 2014;38:1230-1236.