Blood Clots During Cancer Treatment

This page is for people in cancer treatment and their caregivers. It covers the warning signs of a blood clot, why cancer raises the risk, and how clots are treated.

When a clot breaks loose and travels to the lungs, it is called a pulmonary embolism, or PE. The CDC says a PE can be life-threatening and requires immediate medical attention.

Call 911 or go to the nearest emergency department right away if you have any of these signs.

• Difficulty breathing.
• Chest pain or discomfort that usually worsens with a deep breath or cough.
• Cough, or coughing up blood.
• A faster than normal or irregular heartbeat.
• Very low blood pressure, lightheadedness, or fainting.

The CDC's instruction is direct: seek immediate medical attention if you have any signs of a possible PE. MedlinePlus says to go to the emergency room or call 911 or the local emergency number. NHLBI says a PE can cause death if a clot is large or there are many clots. This is not something to sit with until the clinic opens. In practice that means calling 911, or your local emergency number, for trouble breathing, chest pain, fainting or collapse, or a racing heart — not driving yourself and not leaving a message. For a suspected clot in a leg or arm without those features, call your care team right away.

A clot in a deep vein, most often in the lower leg, thigh, pelvis, or arm, is called a deep vein thrombosis, or DVT. The CDC lists these signs.

• Swelling of the affected limb.
• Pain or tenderness not caused by injury.
• Skin that is warm to the touch, red, or discolored.

These usually appear in only one limb. The American Cancer Society describes the pattern as pain, redness, swelling, and warmth, especially if it is in only one arm or leg.

If you notice this, the CDC says to alert your cancer doctor as soon as possible. Call right away, even if you feel well otherwise. The CDC also notes that about half of people with a DVT have no symptoms. A new swollen leg deserves a call, not a wait-and-see week.

The CDC states plainly that having cancer, and some of its treatments, increases the risk of a blood clot. Risk is higher with cancers of the pancreas, stomach, brain, lungs, uterus, ovaries, and kidneys, and with lymphoma and myeloma. On the treatment side, hospitalization, surgery, chemotherapy, hormonal therapy, and catheters all raise risk.

Other factors add to that: a previous clot, an inherited clotting disorder, long periods without moving, obesity, smoking, and some chronic illnesses. The NHLBI notes that risk is highest after major surgery, major injury, or during periods of infection and inflammation. Lack of movement after surgery, or while traveling long distances, contributes too.

The CDC also says something worth keeping in view: blood clots are often preventable and treatable.

A port, PICC line, or other central venous catheter sits inside a vein. The CDC counts catheters among the cancer treatments that raise clot risk. The American Cancer Society lists having a central line as a risk factor for clots.

Because these lines run through an arm or chest vein, a catheter-related clot tends to show up as pain, redness, swelling, or warmth in the arm on that side. Call your care team right away for pain, redness, swelling or warmth in that arm, the same as for a swollen leg.

Most clots are treated with anticoagulants, often called blood thinners. Your team decides which drug, at what strength, and for how long. The American Cancer Society explains that these prevent clots from growing and new ones from forming; the body naturally breaks down blood clots over time. The medicine does not dissolve the clot. It holds the clot in place and stops new ones while your body clears it.

For a clot that is life-threatening, doctors may use thrombolytic (clot-busting) medicines that break clots up. The American Cancer Society notes these can cause severe side effects, like heavy bleeding. MedlinePlus also says treatment may involve dissolving or removing the clot, and that a filter may be placed to keep clots from reaching the lungs. The CDC says compression stockings are sometimes recommended after a DVT. The CDC adds that they may need to be worn for two years or more after a DVT.

• What is my clot risk with this cancer and this treatment, and should I be on anything to prevent one?
• Which symptoms mean call the clinic, and which mean go straight to emergency care?
• Who do I contact after hours, and what should I say first?
• If I start a blood thinner, what bleeding signs should I watch for, and what should I avoid?
• Does my port or PICC line change any of this?

Helpful next pages include PICC Line Care at Home, Port Care at Home, Low Platelets During Chemotherapy, and Side Effects of Cancer Treatment.

• Centers for Disease Control and Prevention: Understanding Your Risk for Blood Clots with Cancer. https://www.cdc.gov/blood-clots/risk-factors/cancer.html.
• Centers for Disease Control and Prevention: About Venous Thromboembolism (Blood Clots). https://www.cdc.gov/blood-clots/about/index.html.
• National Heart, Lung, and Blood Institute: Venous Thromboembolism. https://www.nhlbi.nih.gov/health/venous-thromboembolism.
• MedlinePlus (National Library of Medicine): Pulmonary Embolism. https://medlineplus.gov/pulmonaryembolism.html.
• American Cancer Society: Blood Clots. https://www.cancer.org/cancer/managing-cancer/side-effects/low-blood-counts/blood-clots.html.