Blood clots often occur in people with lung cancer. Lung cancer can also cause deep vein thrombosis (DVT), a type of clot that can break loose and travel to the lungs (pulmonary embolism).

Cancer greatly increases the risk of developing various types of blood clots, including DVT and pulmonary embolism (PE).

Both DVT and PE are potentially deadly. DVT develops in a deep vein, usually in the legs. PE occurs when a blood clot such as DVT breaks free and travels to the lungs.

The authors of a 2018 review of research concluded that 3.7% of people with lung cancer develop PE. Among all PEs they included in the review, the authors found that 29.4–63% were unsuspected. This means that a doctor found an unsuspected PE on a scan they ordered for other purposes, not because they thought the person might have PE.

In fact, doctors may treat PE symptoms as symptoms of lung cancer or as side effects of lung cancer treatments, according to an older review from 2014. This may be because the two conditions cause similar symptoms.

As a result, a doctor may not initially suspect PE. They may later diagnose an unsuspected PE when scanning the lungs to assess treatment effectiveness. Some people with unsuspected PE may not have any symptoms.

The following sections outline everything a person needs to know about how blood clots relate to lung cancer.

All people with cancer are at risk of developing DVT and PE. Experts say this may be because cancer tumors damage tissues involved in blood clotting.

Research associates lung, colorectal, and pancreatic cancers with the highest risk of blood clots. The same 2018 review concluded that lung cancer is the most likely cancer to coexist with a blood clot in the lungs. The authors found that doctors most often diagnose blood clots in the lungs within 6 months of making a lung cancer diagnosis. People with cancer that has metastasized (spread) have a higher risk of PE.

Some cancer treatments also increase the risk of clotting, including:

  • vascular endothelial growth factor (VEGF) inhibitors, such as bevacizumab
  • VEGF tyrosine kinase receptor inhibitors, such as sorafenib and sunitinib
  • lenalidomide
  • tamoxifen
  • platinum-based chemotherapy, such as cisplatin
  • L-asparaginase
  • thalidomide

Additional DVT risk factors include:

  • having another condition that increases the risk of blood clots
  • having a blood transfusion
  • receiving some anemia treatments
  • smoking
  • being over the age of 65 years
  • sitting or lying down for a very long period
  • being pregnant
  • using birth control or other hormonal therapies
  • having a family history of blood clots
  • having overweight
  • recently undergoing surgery
  • having an infection
  • having a central venous catheter

Having a blood clot that travels to the lungs (PE) can be fatal and requires immediate medical attention.

Prompt medical attention gives a person a high likelihood of surviving. Treatment for PE typically involves preventing future clots. The body then resorbs the existing clot.

Doctors will usually inject blood thinners and then prescribe oral blood thinners. These drugs will not break up an existing clot, but they usually help prevent new clots from forming.

More serious blood clots may require hospitalization. A doctor may suggest surgery to remove the clot or to insert a device that prevents clots from traveling to the lungs.

DVT is a dangerous type of blood clot that usually forms in the legs, though it can occur in other areas of the body. All people with cancer are at risk of developing DVT. However, people with lung cancer are at a higher risk of developing both DVT and PE.

Treatments for DVT include:

  • anticoagulants, or blood thinners
  • an inferior vena cava filter, which is a device that healthcare professionals insert into the arteries to catch a clot before it reaches the lungs
  • thrombectomy or embolectomy — a surgical procedure to remove the clot from the legs or the lungs, respectively

Coughing up blood is one symptom of PE. Other possible symptoms include:

  • pain in the chest
  • shortness of breath that often comes on suddenly, especially after activity
  • lightheadedness
  • rapid heartbeat
  • loss of consciousness

Prompt medical attention and continued treatment help prevent death due to PE. Ongoing treatment can involve both lifestyle changes and medications such as blood thinners.

However, one 2018 review concluded that people with PE and lung cancer may have a shorter survival time than those who have only lung cancer.

A 2020 study suggested that for older adults with both conditions, the median survival time was around 4 months.

A 2018 study noted that, among people with cancer and PE, the chance of surviving for 1 year was 60%.

All situations are unique. A person with lung cancer and PE should talk with their doctor about their outlook.

Does lung cancer cause clots?

Having lung cancer or other types of cancer can increase the risk of developing blood clots. This can occur due to tissue damage that affects blood clotting, some cancer treatments, and other conditions that cause blood clots.

What is the life expectancy with blood clots in the lungs?

A person’s outlook with blood clots in the lungs can depend on the size and location of the clots, the treatment type, and other health conditions a person may have. If a person does not receive treatment, PE can result in death. Treatment and lifestyle changes may help reduce the risk of a repeat event.

What is the prognosis for pulmonary embolism in lung cancer patients?

A person’s prognosis for PE and lung cancer can depend on many factors, including the cancer stage and the person’s age. A 2020 study found that for older adults with both conditions, the median survival time was around 4 months.

What happens in the final days of lung cancer?

In the final days of end stage lung cancer, a person may experience pain, fatigue, shortness of breath, and loss of appetite and thirst.

Is there a specific cause for a pulmonary embolism?

A PE happens when a blood clot develops in the lungs or when one develops in a deep vein and then breaks off and travels to the lungs. Blood clots can occur due to damaged veins, inflammation, cancer, and other causes.

What are the early warning signs of a pulmonary embolism?

A person with PE may experience symptoms such as shortness of breath, rapid breathing and heart rate, coughing, and pain when breathing deeply.

What happens after a pulmonary embolism diagnosis?

After diagnosing PE, a doctor may prescribe blood thinners or other medications. In some cases, a person may need a procedure to remove the clot.

Lung cancer and cancer treatments can increase a person’s risk of developing a blood clot in the legs (DVT) that travels to the lungs (PE). People with both lung cancer and PE have an overall shorter survival time, but prompt treatment can help significantly.