A stroke happens when a blood vessel that feeds the brain either gets blocked by a clot or ruptures, cutting off the brain’s blood supply.

A stroke occurs when a blood vessel that feeds the brain either gets blocked by a clot (ischemic stroke) or ruptures (hemorrhagic stroke), cutting off the brain’s blood supply. Most strokes result from a clot rather than a rupture. A stroke is a medical emergency: The longer the brain goes without its supply of oxygen-rich blood, the more healthy tissue will be lost.

Some breast cancer treatments have been associated with increased stroke risk:

  • Tamoxifen: Some studies have found that there is a small but real increase in stroke risk in women who take tamoxifen, probably due to the increased risk of blood clot formation. However, there are other studies suggesting no increased risk of stroke among women taking tamoxifen. Still, if you take tamoxifen, you need to be aware of a possible increased risk of stroke.

  • Procrit (chemical name: epoetin alfa), Epogen (chemical name: epoetin alfa), and Aranesp (chemical name: darbepoetin alfa): These all belong to a class of medications known as erythropoiesis-stimulating agents, or ESAs. They may be used to boost red blood cell production during chemotherapy, which can help with side effects such as anemia and fatigue. There is strong evidence that these medications increase the risk of stroke as well as heart attack (blockage of a coronary artery that supplies blood to the heart). Therefore, they should be used only for select patients when absolutely necessary and at the lowest dose possible.

  • Avastin (chemical name: bevacizumab): Avastin is a targeted therapy that was approved by the U.S. Food and Drug Administration (FDA) in 2008 to be used in combination with Taxol (chemical name: paclitaxel) to treat metastatic HER2-negative breast cancer that hadn’t been treated with chemotherapy yet. Still, in 2011, the FDA removed the breast cancer indication from Avastin because the medicine had not been shown to be safe and effective for that use. Avastin has not been removed from the market and doctors can choose to use Avastin to treat metastatic breast cancer whether or not that particular use is officially approved by the FDA. Avastin is approved by the FDA to treat advanced-stage cancer of the lung, colon, and rectum. Research has shown that Avastin may cause severe stroke or heart problems, including blood clots, heart attack, weakening of the heart, and chest pain.

What about other SERMs? Tamoxifen belongs to a class of estrogen-targeting medications known as selective estrogen response modifiers (SERMs), which also include Fareston (chemical name: toremifine) and Evista (chemical name: raloxifene). Right now, Fareston appears to pose an even lower risk of stroke than tamoxifen does. Some studies haven’t found that Evista increases stroke risk, but others have. One study found that the risk of a fatal stroke was slightly higher in postmenopausal women who were taking Evista and who already had risk factors for coronary artery disease.

If your doctor recommends Procrit, Epogen, or Aranesp as part of your treatment plan, ask why you need to have it.

If Avastin or tamoxifen (or another SERM) is part of your treatment plan, you and your doctor should talk about any risk factors you already have for stroke, such as:

  • your age: being 55 or older means higher risk

  • a family history of stroke

  • previously having had a stroke, a TIA (transient-ischemic attack, which produces stroke-like symptoms but no lasting damage), and/or heart attack

  • your ethnicity: Blacks are at higher risk of fatal stroke

  • high blood pressure

  • cigarette smoking

  • diabetes

  • artery disease anywhere in the body, such as the carotid arteries in the neck or peripheral arteries that supply leg and arm muscles

  • atrial fibrillation (heart rhythm disorder) or other conditions affecting the heart, such as heart failure or an enlarged heart

  • sickle cell disease

  • high blood cholesterol

  • lack of exercise

  • a diet high in salt, fat, and cholesterol

  • being overweight or obese

Talk to your doctor about how to improve any lifestyle-related risk factors. If you have multiple risk factors for stroke, though, your doctor may recommend other treatments besides tamoxifen.

Also, learn the warning signs of stroke and call 911 if you experience any of them. According to the American Stroke Association, these include:

  • sudden numbness or weakness of the face, arm, or leg, especially on one side of the body

  • sudden confusion, trouble speaking or understanding

  • sudden trouble seeing in one or both eyes

  • sudden trouble walking, dizziness, loss of balance or coordination

  • sudden, severe headache with no known cause

Ischemic strokes, which are caused by blood clots, often can be treated with clot-busting drugs given through an IV, but treatment has to start within 3 hours of the onset of symptoms. That’s why getting emergency medical help is so important.

— Last updated on August 2, 2022, 3:42 PM