A pulmonary embolism (PE) is a blood clot (or thrombus) that travels from the leg, pelvis or arm into the pulmonary artery and blocks blood delivery to the lungs. Among non-hospitalized cancer patients being treated with chemotherapy, approximately 3% of deaths are caused by PE. Among hospitalized cancer patients, up to 10% of deaths are caused by PE.
Pulmonary embolism causes
A pulmonary embolism usually starts as a blood clot in the leg or pelvis, where the clot is called a deep vein thrombosis (DVT). If a piece of the clot breaks off from the vein and travels (embolizes), through the circulatory system to the pulmonary artery, it can block the supply of blood to the lungs. At that point, it is called a pulmonary embolism.
There are many things that lead to the formation of a deep vein thrombosis/pulmonary embolism in cancer patients. Some types of cancer are more likely to cause these clots, including:
- acute leukemia
- brain cancer
- breast cancer
- colorectal cancer
- gynecological cancers
- kidney cancer
- lung cancer
- pancreatic cancer
The risk of clotting increases as the cancer grows and spreads in the body.
Several cancer treatments can also lead to blood clots, such as chemotherapy and hormone therapy. Patients who are older, undergo surgery, are immobile, obese or who have central venous catheters are at an increased risk of developing these clots.
Pulmonary embolism symptoms
The main symptoms of a deep vein thrombosis are pain and swelling in the calf, behind the knee and up into the thigh, all in one leg. The main symptoms of a pulmonary embolism are sudden shortness of breath and chest pain.
Deep vein thromboses and pulmonary emboli are diagnosed by imaging exams. Ultrasound/Doppler study is used for a deep vein thrombosis and chest CT angiography for a pulmonary embolism.
Pulmonary embolism treatment
For both deep vein thromboses and pulmonary emboli, patients are given blood thinners (anticoagulants) to prevent new clots from forming and existing clots from spreading. This gives the body a chance to digest the dangerous clot and heal itself.
The most commonly used anticoagulants are pills that need to be taken once or twice per day, although sometimes an anticoagulant that is injected under skin is prescribed. The main side effects of these medications are bruising and bleeding. In most cases these medications can be taken with any type of food and no blood testing is needed to ensure that they are working properly. Blood thinning medications are usually continued for as long as a patient is being treated for cancer, although the dose of medication can sometimes be reduced after six months.
How the body heals depends on where the clot is located. A pulmonary embolism usually dissolves during anticoagulation treatment. A deep vein thrombosis often does not clear up entirely. It will heal, however, when the body covers it with fresh layers of cells that smooth it over, stabilize it and protect the blood vessel from forming new clots. Walking and wearing over-the-counter compression stockings during the day will help the leg vein repair itself.
What are some symptoms of a blood clot?
- Swelling in the calf or thigh
- Tenderness at the back of the leg anywhere between your heel and buttocks
- Leg cramps
- Redness of lower leg or around a venous catheter in the arm or leg
- Swelling in one arm, especially an arm on the side of a central venous catheter or peripherally inserted central catheter (a long, thin tube that's inserted through a vein in your arm and passed through to the larger veins near your heart)
- Sudden difficulty breathing
- Sudden localized chest pain
- Chest pain that worsens with coughing or taking a deep breath
- Racing heart
Is there a specific cause for a pulmonary embolism?
Cancer, chemotherapy, immunotherapy, hospitalization, obesity, infections, medications, venous catheters and acute sicknesses can all contribute to the cause of a PE. A single PE cause is sometimes never found. Because so many different things cause a PE and most of them can’t be eliminated or easily fixed, it is important to try to prevent them.
To prevent PE or deep venous thrombosis (DVT) when patients are in the hospital, a combination of compression stockings, pneumatic compression devices and/or blood thinning medications are used. Outside of the hospital patients are prescribed blood thinning medications. When blood thinning medications are used to prevent PE and DVT, the doses used are lower than those used to treat PE and DVT.
What are the early warning signs of a pulmonary embolism?
The early warning signs of PE are difficulty breathing and localized chest pain that may get worse when coughing or taking a deep breath. These signs usually develop suddenly and often don’t go away. But sometimes the signs are less prominent, such as new, mild shortness of breath when walking or exercising, and chest pain that comes and goes.
What happens after a pulmonary embolism diagnosis?
Most PE patients are hospitalized briefly and prescribed blood thinning medications. Some patients experience injury to the heart or shock because of the PE and will be admitted to an intensive care unit. There, a team of cardiologists, pulmonologists, hematologists, interventional radiologists and vascular surgeons, called the Pulmonary Embolism Response Team (PERT), work together to manage the condition.
After hospital discharge, patients will stay on a blood thinning program that is working (no new PEs) and safe (no dangerous bleeding). Many cancer patients find this difficult, particularly when the medication requires an injection. It is very important that the health care team and patient maintain good communication about overall health changes and new symptoms, as a second (or recurrent) PE is more lethal than the first one.
What happens to the body after a pulmonary embolism?
Most pulmonary emboli will dissolve during the first four weeks after beginning anticoagulation medication. Shortness of breath and chest pain usually go away over the course of three to four weeks. Many patients suffer anxiety because they fear having another pulmonary embolism. However, new or recurrent PE occurs in fewer than 10% of patients who take blood thinning anticoagulant medications as prescribed. Over 90% of patients who are treated for PE survive.