Pulmonary Embolism in People With Blood Cancer

Symptoms of pulmonary emboli—blockages in arteries to the lungs that are usually caused by blood clots—can vary greatly. Depending on how much of your lung is involved and the size of the blockage, you may experience some of the common signs and symptoms, such as the following:

• sudden shortness of breath that gets worse with exertion
• Chest pain that may become worse when you breathe deeply
• Pain when you cough, eat, bend, or stoop
• Pain that worsens with exercise but doesn’t completely go away when you rest
• Cough, which may bring up bloody mucus

Other signs and symptoms, which may include the following:

• Leg pain or swelling, or both, often in the calf
• Clammy skin or blue-tinged skin
• Fever
• Sweating
• Rapid or irregular heartbeat
• Lightheadedness or dizziness

What Happens During a Pulmonary Embolism

During a pulmonary embolism or PE, the most typical scenario is that a blood clot gets pumped out of the heart to the lungs, via the pulmonary artery. The pulmonary artery branches to deliver blood to each lung and blood clots can become lodged at various points along the way, in the vessels that conduct blood to the lungs. If a blood clot is large enough, it can get stuck and completely obstruct a large vessel, which may be life-threatening. It is also possible for a blood clot to be so small that it essentially goes unnoticed, causing only a tiny piece of the lung to feel its effects.

Diagnosis and Treatment

A variety of tests may be done to diagnose pulmonary emboli, including a ventilation-perfusion scan, a high resolution CT scan, or a pulmonary angiogram.

Treatments for pulmonary emboli depend on the severity and extent of the clot. If symptoms are not severe, blood thinners may be used and precautions to prevent further development of clots are taken. For large, severe clots, clot-busting medications like those used to open up heart vessels during a heart attack may be used.

Why Patients With Cancer Are at Risk

When scientists study the risk of PE, they consider the whole disease entity that typically sets a person up to have them. That is, PEs are one of several events that can occur when a person develops blood clots in their veins, a condition known as venous thromboembolism, or VTE.

Compared to the general population, the incidence of VTE and PE is higher in patients with cancer; cancer patients are about four times as likely to develop venous thromboembolism, which includes both pulmonary embolism and deep vein thrombosis. Deep vein thrombosis, or DVT, refers specifically to blood clots that form in the deep veins, typically in the legs, but they can also occur elsewhere. The most serious complication of DVT happens when a part of the clot breaks off and travels through the bloodstream to the heart and subsequently the lungs, causing the blockage known as PE. You can have a PE without having a DVT, however.

In general, these blood clots may form in your body's deep veins for a variety of different reasons, including the following:

• Damage to a vein’s inner lining
• Injuries to the vein caused by physical, chemical, or biological factors
• Having surgery, sustaining a serious injury, having an illness or condition that produces inflammation, and also certain immune responses
• An illness or condition in which the flow of blood slows down, such as after surgery, or during prolonged bed rest, or during a long flight while traveling
• Certain conditions that cause your blood to be thicker or more likely to clot than normal
• Certain inherited conditions, for instance, factor V Leiden, which increases your risk of blood clotting
• Hormone therapy or birth control pills

Clotting and Bleeding in Patients With Cancer

Blood clots are common in patients with cancer, and cancer patients may be at increased risk of blood clots for a variety of reasons, including cancer, itself, and also various treatments for cancer. Chemotherapy, radiation therapy, and hormone therapy may all increase the risk of blood clots.

It may seem counterintuitive, but bleeding disorders may also be more common in people with blood cancer. This can be understood as follows: generally, when there is a problem with the body’s clotting system, a person may be at risk for either excessive bleeding or clotting, depending on the circumstances.

The Role of Clot-Preventing Medication

Routine clot-preventing medication is not recommended in outpatients with cancer, especially those deemed at low risk for VTE; however, in those at higher risk for VTE and in those with myeloma receiving drugs called immunomodulators, such clot-preventive medication could be considered, according to expert groups.

The current standard of care is something called low-molecular-weight heparin (LMWH), which requires injections. Other, newer oral blood thinners are available, but there is limited evidence for healthcare providers to draw upon when considering making the switch from LMWH to one of these oral agents.

In a recent study, when given a hypothetical choice of LMWH versus an oral agent with equal efficacy, most patients with cancer understandably chose the oral agent. Experts say, however, that the decision to switch requires careful consideration of the interplay between the patient’s cancer and treatment course, with their underlying comorbidities.

PE/VTE in Patients With Specific Blood Cancers

Early studies suggested that solid tumors such as breast cancer and lung cancer were, in general, more likely to increase the risk of blood clots than the blood cancers, which include leukemia, lymphoma, and myeloma. There have been other studies since that counter this notion, however, and it may be the case that the types of blood cancer and individual patient characteristics influence your risk in important ways.

Elderly Patients With Chronic Myeloid Leukemia

A study published in 2016 suggested that elderly patients with CML had greater rates PE than patients without cancer, which was not necessarily surprising, since cancer, in general, is thought to increase clotting problems. The rates of clotting problems were not increased in the group of patients taking drugs called tyrosine kinase inhibitors (mostly one named imatinib), though, suggesting that the risk in these patients with CML was driven mostly by the underlying factors associated with the cancer and not the treatment.

Childhood Acute Lymphoblastic Leukemia

Pulmonary embolism in during childhood is uncommon, but having a malignancy (such as leukemia) can increase the risk VTE and PE in children. Big risk factors for VTE and PE include a central venous catheter, malignancies, and chemotherapy. VTE occurs in 2.1–16% of children with cancer, whereas reported rates of catheter-related VTE range from 2.6 to 36.7%.

Much of the evidence of PE in children with cancer focus on patients with ALL, the most common pediatric malignancy. A meta-analysis of children with leukemia reported VTE in 5.2% of children with ALL, but reported rates ranged from 1 to 36%. In particular, the use of L-asparaginase, along with the chemotherapy regimen including anthracycline, vincristine, and steroid, has made acute lymphocytic leukemia (ALL) a curable malignancy, particularly in children—but it may also be associated with increased risk of VTE, so medicines to prevent blood clotting may be given to reduce this risk.

Acute Promyelocytic Leukemia, a Type of AML

Compared to bleeding, major blood clots are a less common problem in patients with acute promyelocytic leukemia, a rare type of AML. This is a good example of a blood cancer in which the body’s coagulation systems are affected, often leading to bleeding, but also with the possibility of clotting. Patients with acute promyelocytic leukemia might go to the healthcare provider with problems with bleeding such as a nosebleed that won’t stop, or a cut that won’t stop oozing. But they may also have calf swelling from a DVT, or chest pain and shortness of breath from a blood clot in the lung or PE.

Clotting Risk in Leukemia and Lymphoma

A study by Petterson and colleagues published in 2015 suggested that all types of cancer tend to increase the risk of VTE and that the extent of the increased risk is different for different major categories of cancer; in this particular study, the lowest risk of VTE was seen with head and neck cancers (4.1x) and the highest risk was seen with brain cancer (47.3x).

When this group of researchers tried to adjust for multiple variables to get a sense for the risk of VTE in lymphoma (relative to other cancers), they found the risk was particularly increased among lymphoma patients.

Lymphoma was among the four cancer sites with the particularly increased risk of VTE, as follow:

• Brain cancer
• Pancreatic cancer
• Other digestive (esophagus, small intestine, gallbladder, and bile system)
• Lymphoma 

Patients with leukemia were found to be at intermediate risk in this study.

Of the 33 incident cases with active lymphoma and 18 incident cases with active leukemia in this study, only 14 of 50 (28%) had a central venous catheter within the three months prior to the VTE event. Most of the incident cases with active leukemia had chronic lymphocytic leukemia (11 of 18, or 61%), which is not typically treated with L-asparaginase, a known risk factor for VTE.

A Word From Verywell

It’s important to know that, as a cancer patient, you may be at greater risk for problems with blood clots such as pulmonary embolism. However, it is also important to put this risk in perspective. Overall, the chances of developing a pulmonary embolism are still quite low.

Although receiving treatment through a central venous catheter may increase the risk of PE/VTE, such treatment may be life-saving for many patients with cancer. Physicians are aware of the risks for VTE/PE in various presentations of blood cancer, and with various treatments and interventions. As an educated patient, your knowledge of the symptoms of PE/VTE and your vigilance can help your healthcare provider act quickly, should the need arise.