MPNs are a group of rare, chronic blood cancers in which the patient’s bone marrow produces abnormal blood cells. This can cause a host of symptoms and complications. As these conditions are chronic in nature, they can last for a long period of time. They are are also progressive in nature and may worsen over time.
MPNs can be classified according to the absence of presence of a chromosomal abnormality called the Philadelphia chromosome. Philadelphia chromosome negative MPNs include Polycythaemia Vera (PV), Essential Thrombocythaemia (ET) and Myelofibrosis (MF).
- Polycythaemia Vera (PV)
- Essential Thrombocythaemia (ET)
- Myelofibrosis (MF)
Polycythaemia Vera (PV)
PV is a rare, chronic blood disease in which a person’s body makes too many red blood cells. This may also be accompanied by too many white blood cells and/or platelets. Too many red blood cells can cause the blood to be too viscous and block the flow of the blood through arteries and veins. This can result in a heart attack or stroke.
The main cause of PV is a genetic mutation in the Janus Kinase 2 (JAK2) gene.
Other serious complications from PV may include:
- Blood clots leading to a heart attack or stroke
- Stomach ulcers, gout or kidney stones
- Chest pain
- Progression to leukaemia
- Progression to another MPN ( MF)
Leukaemic transformation rates at 20 years are estimated to be less than 10% for PV patients, and 15% of patients with PV progress to MF.
Essential Thrombocythaemia (ET)
ET is a rare blood disease in which a person’s body generates too many platelets. These platelets may not function appropriately and cause a blockage in blood vessels ( thrombosis), or less commonly, bleeding problems.
The cause of ET is not fully understood but 3 specific mutations have been identified in patients with ET. These mutations are the Janus Kinase 2 (JAK2), Calreticulin ( CALR) and mutation of the thrombopoietin receptor ( MPL).
Serious complications from ET may include:
- Clotting complications
- Pregnancy complications
- Excessive bleeding
- Heart attack
- Progression to another MPN, such as myelofibrosis (MF)
- Progression to acute leukaemia
ET patients have an excellent chance at longevity if monitored and treated properly, and about 15% of ET patients may progress to MF.
Leukaemic transformation rates at 20 years are estimated to be about 5% for ET patients.
MF is a chronic blood cancer in which scar tissue forms in the bone marrow and reduces its ability to produce normal blood cells. It may be associated with certain genetic mutations such as the Janus Kinase 2 (JAK2) mutation. In MF, the scarring of the bone marrow leads to reduced production of normal blood cells.
Other complications from MF may include:
- Heart attack or stroke
- Increased pressure on blood flow to the liver (portal hypertension)
- Bleeding complications
- Progression to leukaemia (10 year risk of transformation to acute leukaemia is approximately 20% for MF patients)
The prognosis of MF is different for every patient. While some live for many years without developing major symptoms or complications, others may find that their disease progresses more quickly.
Factors that influence MF prognosis are age, white blood cell counts, number of immature white blood cells ( also known as blasts or leukaemic cells) in the blood, constitutional symptoms (e.g night sweats, weight loss, fever), low red blood cells, transfusion dependence, low platelet count and abnormal chromosomal analysis.
Your doctor will need to monitor you closely and will discuss your individual prognosis based on the relevant factors.