Cancers that lead to thick blood, medically known as hyperviscosity, are primarily those affecting the production of blood cells or certain proteins in the blood. The most common cancer directly associated with an overproduction of red blood cells, leading to thick blood, is polycythemia vera.
Understanding Thick Blood (Hyperviscosity)
Thick blood, or hyperviscosity syndrome, occurs when the blood's viscosity (thickness) increases, making it harder for blood to flow through the vessels. This can lead to a variety of symptoms, including headaches, dizziness, vision problems, and a significantly increased risk of blood clots, strokes, and heart attacks.
Cancers Directly Causing Thick Blood
Several types of cancer can cause the blood to become unusually thick. These generally fall into two main categories: those that cause an overproduction of blood cells and those that cause an overproduction of proteins.
1. Polycythemia Vera (PV)
Polycythemia vera is a chronic leukemia, a type of blood cancer originating in the bone marrow. It is characterized by the bone marrow producing an excessive number of red blood cells. This overproduction of red blood cells significantly increases the blood's thickness.
- Progression: Polycythemia vera typically progresses very slowly and is often diagnosed in individuals over the age of 60.
- Management: While serious, many people with polycythemia vera can manage their symptoms effectively for many years with appropriate treatment.
- Primary Risk: The primary concern with an excess of red blood cells is the heightened risk of developing dangerous blood clots, which can lead to life-threatening events such as deep vein thrombosis (DVT), pulmonary embolism, stroke, or heart attack.
2. Other Myeloproliferative Neoplasms (MPNs)
Polycythemia vera is one of several myeloproliferative neoplasms (MPNs), which are a group of slow-growing blood cancers that cause the bone marrow to produce too many blood cells. While PV specifically targets red blood cells, other MPNs can also contribute to hyperviscosity:
- Essential Thrombocythemia (ET): Characterized by an overproduction of platelets. While platelets are not red blood cells, extremely high platelet counts can also increase the risk of blood clots and, in some cases, contribute to hyperviscosity.
- Primary Myelofibrosis (PMF): Involves the buildup of scar tissue in the bone marrow, leading to abnormal blood cell production. While it often causes low blood counts, in some phases, it can lead to an increase in certain cell types or contribute to overall blood viscosity issues.
3. Plasma Cell Dyscrasias
These are cancers that involve plasma cells, a type of white blood cell that produces antibodies (proteins). An overproduction of abnormal proteins can significantly thicken the blood.
- Waldenstrom's Macroglobulinemia (WM): This is a rare, slow-growing non-Hodgkin lymphoma that causes plasma cells to produce large amounts of an abnormal antibody called IgM. The large size and quantity of these IgM proteins can lead to a dramatic increase in blood viscosity, often causing a condition specifically called hyperviscosity syndrome.
- Multiple Myeloma: While less common than Waldenstrom's for causing severe hyperviscosity, multiple myeloma is a cancer of plasma cells that produce abnormal antibodies (paraproteins). In some cases, high levels of these paraproteins, particularly IgA or IgG, can lead to hyperviscosity syndrome.
Symptoms of Thick Blood
Recognizing the symptoms of thick blood is crucial for early diagnosis and intervention. Common signs include:
- Neurological: Headaches, dizziness, vertigo, confusion, changes in mental status, seizures, and stroke-like symptoms.
- Visual: Blurred vision, double vision, loss of vision.
- Bleeding: Easy bruising, nosebleeds, bleeding gums.
- Circulatory: Chest pain, shortness of breath, fatigue, weakness, numbness or tingling in extremities, cold hands and feet.
Treatment and Management
Treatment for thick blood caused by cancer focuses on managing the underlying cancer and reducing blood viscosity.
- Phlebotomy: For polycythemia vera, regularly removing blood (therapeutic phlebotomy) helps reduce the number of red blood cells and thin the blood.
- Medications:
- Chemotherapy or Targeted Therapy: To reduce the production of abnormal cells or proteins (e.g., hydroxyurea for MPNs, chemotherapy for lymphomas or myeloma).
- Blood Thinners (Anticoagulants): To prevent blood clots.
- Plasmapheresis: For conditions like Waldenstrom's macroglobulinemia, this procedure removes excess proteins from the blood, rapidly reducing viscosity.
Understanding these conditions is vital for those experiencing symptoms of thick blood, as prompt diagnosis and treatment can significantly improve outcomes and prevent serious complications.
