A blood clot in the lungs called a pulmonary embolism led to the beloved actor’s death, with rectal cancer listed as an underlying cause. Here’s what to know.
Catherine O’Hara, the Emmy- and Golden Globe–winning actor best known for her roles in Schitt’s Creek, Home Alone, and Beetlejuice, died of a type of blood clot called a pulmonary embolism, with rectal cancer listed as an underlying cause, according to a death certificate released this week. She was 71.
At the time of O’Hara’s death, on January 30, her representatives said she had been briefly ill. The newly released certificate offers more clarity on the health issues that led to her death.
A pulmonary embolism, often called a PE, is a serious and sometimes fatal condition. While it can affect anyone, cancer and cancer treatments can significantly increase the risk.
What Is a Pulmonary Embolism?
A pulmonary embolism is a blood clot that usually forms in the veins of the legs before breaking free and traveling up through the heart and getting lodged in the lung arteries, says Geoffrey Barnes, MD, a cardiologist and an associate professor at the University of Michigan Medical School in Ann Arbor.
“When it lodges in the lung arteries, it blocks blood flow to that part of the lung, preventing the lung from exchanging carbon dioxide for oxygen and causing pressure to build inside the heart,” says Dr. Barnes.
This blockage can sharply reduce blood flow, strain the heart, and limit oxygen levels in the body.
Pulmonary embolism is a type of venous thromboembolism, which also includes deep vein thrombosis. The precise number of people with a pulmonary embolism or deep vein thrombosis is unknown, but as many as 900,000 people in the United States may be affected. These clots can be life-threatening and cause as many as 100,000 deaths each year, but prompt diagnosis and treatment greatly improve survival.
How Cancer Can Lead to Pulmonary Embolism
Pulmonary embolism is a common complication of cancer, says Barnes. It’s estimated that about 1 in 5 cases of blood clots in the veins are related to cancer and cancer treatment.
“PE is also the second most common cause of death for people with cancer, after the cancer itself,” says Barnes.
People with cancer can develop a pulmonary embolism in one of several different ways, he says.
Cancer cells produce chemicals that are known to cause blood clots, called pro-coagulant factors.
Cancer cells release chemicals that cause inflammation, and inflammation is a common cause of blood clots, including pulmonary embolism.
Cancers can grow and compress blood vessels. When this happens, it can damage the lining of the blood vessel or slow down blood flow enough to cause a blood clot to form.
Chemotherapy can also contribute to pulmonary embolism development. “This occurs from a combination of damage to the blood vessel lining, release of clot-promoting materials from cancer cells, and activation of platelets, which form blood clots,” says Barnes.
Pulmonary Embolism Symptoms Can Be Sudden — or Subtle
Symptoms of pulmonary embolism vary widely, depending on the size of the clot and a person’s overall health.
Common symptoms include:
Sudden shortness of breath, even at rest
Wheezing
Sharp chest pain that may worsen with deep breathing
Fainting or sudden dizziness
Coughing, sometimes with blood
Rapid or irregular heartbeat
Excessive sweating,
Fever
Leg pain or swelling, especially in one leg
Pale, clammy, or bluish skin (people with darker skin may appear gray, ashen, or purplish)
In some cases, pulmonary embolism causes few warning signs. About a quarter of the time, sudden death is the first symptom.
Anyone with unexplained shortness of breath, chest pain, or fainting should seek emergency medical care.
How Is Pulmonary Embolism Treated?
Treatment depends on the size of the clot and the patient’s overall condition.
Most people are treated with blood-thinning medications, known as anticoagulants, which prevent existing clots from expanding and reduce the risk of new clots forming, says Samuel Gurevich, MD, a pulmonologist at Cleveland Clinic in Weston, Florida.
“In severe cases, a special, more powerful version of a blood thinner — a ‘clot buster,’ or thrombolytic — can be used to rapidly dissolve it. Unfortunately, this also carries a greater risk of bleeding,” says Dr. Gurevich.
Sometimes larger embolisms can be physically removed from the lung with the use of special catheter techniques, he says.
“In very special circumstances, especially for large, chronic PEs, a special surgery can be performed to clear out the clots, called a pulmonary thromboendarterectomy or PTE,” says Gurevich.
For people who are already bleeding or have other reasons why blood thinners cannot be used, a special filter can be placed in the main vein draining blood from the lower body, called an IVC filter (short for inferior vena cava). This doesn’t treat the PE that is already there, but it can help prevent additional clots from entering the lungs, he says.
Pulmonary embolisms that occur in cancer are treated the same way as other PEs, including with blood thinners, but treatment may need to be extended, or even become lifelong, says Gurevich.
Because the cancer itself may also be prone to bleeding (such as in the brain or colon), treatment with blood thinners may carry an extra level of risk and careful monitoring is required, he says.
Risk Factors for Pulmonary Embolism
Pulmonary embolism is often treatable — but only if it’s recognized.
In addition to cancer and its treatments, risk factors include:
Recent surgery
Prolonged bed rest or hospitalization
Long-distance travel
Smoking
Obesity
Pregnancy
Estrogen-based medications
Personal or family history of blood clots
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
Bryson Taylor D et al. Catherine O’Hara Died From Pulmonary Embolism, Death Certificate Says. The New York Times. February 9, 2026.
Pulmonary Embolism. Mayo Clinic. December 1, 2022.
Emily Kay Votruba has copy edited and fact-checked for national magazines, websites, and books since 1997, including Self, GQ, Gourmet, Golf Magazine,Outside, Cornell University Press, Penguin Random House, and Harper's Magazine. Her projects have included cookbooks (Padma Lakshmi's Tangy Tart Hot & Sweet), self-help and advice titles (Mika Brzezinski's Know Your Value: Women, Money, and Getting What You're Worth), memoirs (Larry King's My Remarkable Journey), and science (Now You See It: How the Brain Science of Attention Will Transform How We Live, Work, and Learn, by Cathy Davidson). She started freelancing for Everyday Health in 2016.
Becky Upham has worked throughout the health and wellness world for over 25 years. She's been a race director, a team recruiter for the Leukemia and Lymphoma Society, a salesperson for a major pharmaceutical company, a blogger for Moogfest, a communications manager for Mission Health, a fitness instructor, and a health coach.
Upham majored in English at the University of North Carolina and has a master's in English writing from Hollins University.
Upham enjoys teaching cycling classes, running, reading fiction, and making playlists.
