Multiple myeloma (also known as myeloma) is a type of blood cancer. It starts with one abnormal plasma cell (myeloma cell) in the bone marrow that multiplies and replaces healthy cells. Research has found that people living with myeloma are at a higher risk of developing blood clots — particularly blood clots that form in the arteries (called arterial thrombosis, or AT) and veins (venous thromboembolism, or VTE). Researchers believe this increased risk may be a side effect of certain treatments for myeloma — they may also be caused by the cancer itself.
Although blood clots can be dangerous, there are some steps you can take to help lower your risk of developing one. Talk to your health care provider or oncology specialist about ways to prevent developing blood clots with myeloma.
Coagulation (normal blood clotting) is usually a helpful and important process that heals wounds and injuries. Clotting involves platelets (thrombocytes) and proteins in the blood called coagulation factors (or clotting factors). These platelets and proteins stick together to control bleeding and heal broken blood vessels.
Damaged or missing clotting factors can cause blood clots (emboli) to form in the blood of a vein or artery. These clots can travel to the lungs, causing a block called a pulmonary embolism. If a clot makes its way to the brain, it can cut off blood flow and potentially cause an ischemic stroke.
Blood clots can develop in any part of the body and travel to any other area. There are several types of blood clots associated with multiple myeloma. Research shows that people with myeloma have a higher risk of VTE and AT, in particular. A health care provider can diagnose the type of blood clot a person has using one or more tests, including blood tests and imaging tests.
Venous thromboembolism refers to a blood clot that forms in the veins. If the affected vein is in the leg, thigh, or pelvis, it is known as deep vein thrombosis (DVT).
It is important to talk to your doctor right away if you notice symptoms of DVT. DVT should be taken seriously and treated promptly, as it can lead to pulmonary embolism.
Symptoms of DVT include:
VTE can delay or complicate chemotherapy treatments, cause disability, and can even be fatal.
Arterial thrombosis refers to a blood clot in an artery. AT is particularly concerning because it can block or cut off blood flow to major organs, such as the brain or heart. In fact, research has found a correlation between AT and the risk of death in those with myeloma.
A pulmonary embolism forms when a blood clot from another part of the body (frequently in the legs) migrates to an artery in the lung. Pulmonary embolism can result in people with myeloma from a blood-clotting problem known as hypercoagulability — having extra-sticky blood that forms clots too easily.
Disseminated intravascular coagulation is another coagulation problem associated with cancer that’s rare but life-threatening. It causes severe bleeding and clotting at the same time.
Both multiple myeloma and its treatments can increase a person’s risk of developing blood clots. Some people living with multiple myeloma are at higher risk of developing blood clots due to certain risk factors, such as their age and medical history. These factors help doctors screen people with myeloma for clot risks so that treatment with anticoagulants (blood thinners) can be used preventively.
People with cancer have a higher risk of blood-clotting disorders. Cancer cells release substances (IL-6 and immunoglobulins) into the blood that cause it to thicken and become sticky. This hypercoagulability increases the chances that blood clots will form.
Myeloma also causes resistance to activated protein C, an anti-clotting molecule, and blocks the process that prevents the formation of clots. This resistance increases the blood’s stickiness. This means that even before starting treatments, people with myeloma are at a higher risk of developing blood clots.
People with multiple myeloma are at an even greater risk of developing clots if they experience amyloidosis (the buildup of harmful abnormal proteins in the heart, liver, and kidney) and hyperviscosity (thicker blood due to high levels of abnormal antibodies).
Other risk factors that increase the risk of blood clots in people with myeloma include:
People with smoldering multiple myeloma or monoclonal gammopathy of undetermined significance also share the risk of VTE and AT.
Cancer treatments can further worsen the hypercoagulability caused by myeloma. Although immunomodulatory drugs — including thalidomide (Thalomid) and lenalidomide (Revlimid) — are effective in treating myeloma, they’ve been found to increase the risk of VTE. This risk is especially high when these drugs are combined with chemotherapy and/or the corticosteroid dexamethasone. Myeloma drugs known as proteasome inhibitors — including bortezomib (Velcade) and carfilzomib (Kyprolis) — can also raise the risk of blood clots.
Other myeloma treatments and procedures linked to an increased likelihood of developing blood clots include:
Some additional factors that can put people with myeloma at risk of developing blood clots include:
Your health care team will assess your unique risk factors for developing blood clots. This is an important step in determining whether you should start anticoagulation medications as a preventive measure.
Anticoagulants are an effective treatment and prophylaxis for blood clots in people living with myeloma. Blood thinners such as warfarin and heparin can be taken in pill form or by subcutaneous injection (injection under the skin).
When taking blood thinners, it is best to avoid other medications that thin the blood and make you bleed more easily, such as anti-inflammatory drugs. This includes over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), unless your doctor approves them.
Some people who use anticoagulants may have an increased risk of bleeding, but for most, this treatment is safe. If you notice any excessive bleeding, report it to your doctor right away. Health care experts also suggest frequent blood tests to check for abnormalities and treatment effectiveness.
If you’re on blood-thinning medication, it is important to avoid injuries because your blood’s ability to clot will be slowed down. This means that even little injuries could cause you to bleed more than usual. Some things you can do to prevent injuries include:
It is important to discuss your risk factors and preventive treatment options with your doctor. Being your own advocate and asking questions is important for understanding how to best weigh the risks of treatments like blood thinners against their benefits.
The American Society of Clinical Oncology recommends discussing the following clot-prevention tips with your doctor:
VTE is the second leading cause of death in people with cancer after cancer itself. Not only can blood clots be deadly — they can also be a sign that cancer has developed, progressed, or relapsed. This means that knowing the signs and symptoms of a blood clot is an important part of living with myeloma. The best chance for effective treatment of blood clots is to notice signs and symptoms right away and not waste any time seeking emergency medical care.
Pulmonary embolism symptoms require urgent medical attention. They may include:
Less common symptoms of pulmonary embolism can also include:
Symptoms of an ischemic stroke (caused by a clot that reaches the brain) also require urgent medical care. You can use the FAST system to check for indications that you or a loved one may be having a stroke:
Contact your health care provider or emergency medical services immediately if you believe you or a loved one may be experiencing the symptoms of a blood clot or stroke.
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Have you experienced blood clots or bleeds while living with myeloma? Is this a complication that worries you? Leave a comment below or start a discussion by posting on MyMyelomaTeam.