Is Myeloproliferative Disorder Considered Cancer?

Myeloproliferative disorders are rare blood and bone marrow cancers. To understand what happens in myeloproliferative disorders or myeloproliferative neoplasms, it is very important to know the components of the blood and bone marrow.

Components of blood

The three important cells of the blood are the red blood cells (RBCs), white blood cells (WBCs), and platelets. All these blood cells are made in the bone marrow and float in a fluid called plasma.

1. RBCs
   • These are components of the blood that account for the major part of the blood cells. 
   • The RBCs help carry oxygen and carbon dioxide to various body parts. 
   • The protein component of RBCs that helps carry oxygen to various parts of the body is called hemoglobin.
2. WBCs
   • Play an important role in fighting against infections. Infections are caused when WBCs decline in number. 
   • WBCs can be categorized into the following:
     • Neutrophils
     • Monocytes
     • Lymphocytes
3. Platelets
   • Are blood cells that are formed in the bone marrow. 
   • These cells help in the formation of blood clots and stop bleeding.

Bone marrow

It is a soft tissue that is present inside the bones. All the blood cells are made in the bone marrow as stem cells. Stem cells are immature cells and when these cells mature, they develop into RBCs, WBCs, and platelets. These blood cells are released into the bloodstream from the bone marrow. The blood that is circulating outside the bone marrow is called peripheral blood.

Six types of myeloproliferative disorders include:

1. Myelofibrosis
   • Affects red blood cells (RBCs) and a type of white blood cell (WBC) called granulocytes. 
   • This is a rare condition where the bone marrow cells get fibrosis and form scar tissue, which inhibits the production of healthy blood cells resulting in various complications.
   • Malformed RBCs result in anemia, which causes fatigue and weakness.
   • Abnormal stem cells may increase or decrease the production of WBCs.
     • Lowering the production of WBCs may decrease the ability to fight against infections.
     • Increased WBCs may increase the viscosity of the blood, leading to severe complications such as stroke.
   • The abnormal stem cells may also result in either excess or low production of platelets. Lower platelet count may result in bleeding and excess production may result in abnormal blood clots.
2. Polycythemia vera
   • A rare condition caused by a gene mutation called Janus Kinase 2.
   • This gene mutation results in the overproduction of RBCs and increases the viscosity of the blood. 
   • The thickened blood may result in decreased blood flow, preventing the required amount of oxygen from reaching the organs. The overproduction of cells may result in abnormal blood clots.
   • The symptoms of polycythemia vera are itchy skin, fatigue, fever, weight loss, and profuse night sweats.
3. Essential thrombocythemia
   • A rare blood disorder that produces an excessive number of platelets.
   • Increased platelet count results in thrombus formation in the blood vessel. This results in severe complications such as stroke and pulmonary embolism.
   • People with essential thrombocythemia have normal life expectancy if monitored and treated properly.
4. Chronic eosinophilic leukemia
   • A condition with an elevated level of eosinophils that fights against allergic reactions.
   • The elevated level of eosinophils results in symptoms such as itching and swelling around the eyes, lips, and swollen hands and legs.
5. Chronic myeloid leukemia
   • Caused by a genetic mutation in the BCR-ABL gene, also called the Philadelphia gene.
   • The mutated gene results in the secretion of the enzyme tyrosine kinase, which initiates the activity and growth of mature and immature white blood cells, called myeloid cells in the bone marrow.
6. Systemic mast cell leukemia
   • Affects the mast cells found in the skin, connective tissues, lining of the stomach, and intestines.
   • In this condition, too many mast cells accumulate in the body tissues and affect the spleen, bone marrow, small intestine, and liver.

The following are the symptoms of myeloproliferative disorders:

• Fatigue
• Weight loss
• Fever
• Itchy skin
• Night sweats
• Bone pain

Severe complications include:

• Excess bleeding
• Blood clots resulting in stroke and pulmonary embolism

Myeloproliferative disorders may not have any symptoms initially, which increases the risk of developing the condition. If anyone is suspected of having myeloproliferative disorders, blood tests and bone marrow biopsy may help confirm the diagnosis.

Myeloproliferative disorders usually cannot be cured. The treatments may help reduce the number of blood cells to normal values to prevent complications. The treatment options vary depending on the type of myeloproliferative disorder.

Some of the common treatment options include:

• Chemotherapy: Uses powerful medications to kill the excess cells. Chemotherapy drugs are administered as an infusion or an injection. Oral chemotherapy is often administered daily, whereas intravenous chemotherapy is typically administered once every few weeks.
• Radiotherapy: High-energy X-rays or other radiations are used to kill the extra cells.
• Phlebotomy: A unit of blood is taken out to decrease the number of red blood cells.
• Gene therapy: A process where the mutated gene is repaired.
• Hormone therapy: Sometimes hormonal imbalances may elevate the number of blood cells. Hormonal therapy may help regulate the number of blood cells.
• Stem cell transplantation: This is one of the effective treatments for myeloproliferative disorders, but it does not suit everyone. In this treatment, stem cells from a healthy donor are transferred to the person with myeloproliferative disorders.