Cancer and the Risk of Blood Clots

diagram of a blood vessel with a blood clot
The risk of blood clots with cancer and how you can lower your risk. istockphoto.com

The risk of developing a blood clot (deep vein thrombosis or DVT) during cancer treatment is very real but often overlooked. The public became more aware of DVTs when TV journalist David Bloom died from a pulmonary embolism while reporting from Iraq, but there is still too little awareness of this common complication of cancer.

Sadly, many cancer survivors who have developed blood clots (which may or may not have traveled to the lungs as pulmonary emboli) did not realize how common (and potentially deadly) this is. Knowing what symptoms you should watch for, and things you can do to lower your risk can go a long way in reducing the chance that this serious complication will interfere with your cancer treatment.

What Are Blood Clots (DVTs)?

A DVT is a blood clot that forms in a deep vein in the body, usually in the legs. If the clot breaks loose, it can travel to the lungs and cause a blockage in the arteries leading to the lungs, a condition known as pulmonary embolism.

How Common Blood Clots (DVTs) Are With Lung Cancer

Between 3 percent and 15 percent of people with lung cancer develop blood clots during their treatment, according to various studies. They are more common in those with non-small cell lung cancer than with small cell lung cancer, and individuals with adenocarcinoma appear to be at the greatest risk. Other factors that increase risk include having an advanced stage of lung cancer (for example stage 4 or metastatic disease) or receiving chemotherapy, especially some of the targeted therapies, or post-surgery. Roughly seven percent of people that have lung cancer surgery will develop a blood clot.

The Importance of Recognizing Blood Clots (DVTs)

It is very important to be on the lookout for blood clots since they can lower survival with lung cancer. In one study, patients with non-small cell lung cancer had a 1.7 fold increased the risk of dying if they had a DVT. Another study found that lung cancer patients who had at least one DVT survived only half as long as those without a DVT. The most dreaded complication of blood clots is that they will break off and travel to the lungs, an emergency situation known as pulmonary embolism, which can be fatal if untreated. Even for clots that do not break loose, you can develop chronic leg pain in the future if they are not treated, something known as post-thrombotic syndrome. Your doctor will check your legs when you are hospitalized, especially after surgery, but the peak incidence of clots following surgery is seven days afterward — a time when many people may be back home recovering.

Blood Clots Can Occur Early After Diagnosis

Even among physicians, there seems to be a feeling that blood clots occur later in the disease or after many treatments. That's not the case. A 2014 study found that over 13 percent of newly diagnosed (within 1 week) had blood clots. Nearly five percent also had pulmonary emboli. 

Situations That Raise the Risk

Having lung cancer alone increases the risk of developing blood clots, but some situations increase the risk further. Some of these include:

  • Surgery surgery can increase the risk of blood clots, but chest surgery (like lung cancer surgery) and abdominal surgery are particularly problematic.
  • Chemotherapy and some targeted therapies
  • Inactivity or prolonged bed rest
  • Other lung diseases such as COPD
  • Smoking
  • Travel. Extended travel by car or plane increases the risk of blood clots. This can be a concern for those who need to travel long distances for treatment

Symptoms

You need to watch for two types of symptoms. Those that are due to a clot in your leg, or those that might suggest a clot has traveled to your lungs (pulmonary embolism).

Symptoms of blood clots in the legs (DVT):

  • None — Occasionally a blood clot is present without any symptoms
  • Leg/calf pain — Especially a cramping type of pain in only one leg
  • Swelling
  • Redness
  • Warmth
  • Pain with extension of your toes — Pain due to a blood clot usually increases if you point your toes toward your head

Symptoms of pulmonary embolism:

  • Chest pain — The chest pain associated with a pulmonary embolism is usually worse with coughing and taking a deep breath
  • Abrupt onset shortness of breath
  • Lightheadedness or fainting
  • Coughing up blood (hemoptysis) — It is very important to be aware of this symptom since lung cancer itself may cause you to cough up blood

When to Alert Your Doctor

Any of the above symptoms should prompt you to call your physician right away. A pulmonary embolism can be fatal, and you should call 911 immediately if you have any symptoms that might suggest you have a pulmonary embolism.

Tips for Prevention

  • Exercise your lower calves when sitting or lying in bed. Point your toes toward your head and back several times
  • When traveling by car, make frequent stops, get out, and walk around the car. When traveling by air, get up and walk around at least every 2 hours
  • After surgery, try to walk as soon as your doctor lets you know it is safe
  • Don’t smoke
  • Drink plenty of water
  • Avoid alcohol and caffeine — Both alcohol and caffeine can dehydrate you and raise your risk
  • If compression stockings (support hose) are recommended, wear these for as long as your doctor advises
  • Watch your blood pressure and salt intake — Elevated blood pressure increases the risk of blood clots, and it can be easy to neglect this more “minor” problem amidst the rigors of cancer treatment
  • Elevate your legs during rest
  • Ask your health care team about methods to lower the risk of blood clots in your particular situation. In some cases, medications are prescribed as well to lower risk

Many of these risk factors occur during travel. If you will be traveling for medical care or for pleasure, check out tips on traveling with cancer.

Diagnosis

The most important part in diagnosing blood clots is to be aware of this possible complication. If you note any symptoms or your physician is concerned, a combination of radiological tests and blood tests can determine if a blood clot is present.

Treatment

The treatment of DVTs and/or pulmonary emboli with cancer includes both reducing the risk of further clotting and dissolving clots that have occurred. Supportive care is also frequently needed, particularly if symptoms such as shortness of breath have occurred with pulmonary emboli.

Treatments may include a combination or the oral medication warfarin and the intravenous or injectable medication heparin, with new medications having been approved in recent years.

A Word From Verywell

Blood clots are far too common among people with cancer and can result in hospitalizations or even death. There are many factors which contribute. Cancer itself sometimes raises risk. Surgery and chemotherapy raise risk. And activities ranging from bedrest to car or air travel for treatment raise risk.

Make sure you are familiar with both the symptoms of blood clots in the legs (deep vein thrombosis) and of blood clots which have traveled to the lungs (pulmonary emboli). Seek help promptly and don't wait if any of these occur. Time can be of the essence. Become familiar with the ways to reduce your risk such as moving your legs frequently. If your oncologist recommends a blood thinner, take her seriously. In retrospect, many people recall events that raised their risk as well as early, but vague symptoms. Blood clots are very treatable if they're found in time.

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