Tumor Emboli
Clumps of cancer cells that travel in the blood and block vessels
Quick Facts
- Type: Cancer-related vascular complication
- What travels: Clusters of tumor cells
- Common site: Small blood vessels of the lungs
- Linked to: Various cancers
Overview
Tumor emboli are clumps of cancer cells that break off from a tumor and travel through the bloodstream until they become lodged in smaller blood vessels. An embolus is anything that travels in the blood and blocks a vessel; in this case the material is made of tumor cells. Tumor emboli most often settle in the small vessels of the lungs, but they can reach other organs depending on the type and location of the cancer.
Tumor emboli are different from the much more common blood clots that occur in people with cancer. They are part of how some cancers spread and can interfere with blood flow in the affected organ. Because they occur in the setting of cancer and can cause symptoms similar to other serious conditions, they may be challenging to recognize. Care is centered on treating the underlying cancer and managing the effects of the blocked vessels.
Symptoms
Symptoms depend on where the tumor emboli lodge and how many vessels are affected. When they involve the lungs, which is common, symptoms can resemble those of a blood clot in the lungs:
- Shortness of breath, sometimes worsening over days to weeks
- Cough
- Chest discomfort
- Low oxygen levels and fatigue
- In severe cases, signs of strain on the heart and lungs
If emboli travel to other organs, symptoms reflect reduced blood flow there. General symptoms of the underlying cancer may also be present.
Causes
Tumor emboli arise from cancers and are part of the process by which some tumors spread through the bloodstream.
- Tumor invasion of vessels: Cancer cells can grow into nearby blood vessels and break off into the circulation.
- Travel through the blood: Clusters of cells move with the blood flow until they reach vessels too small to pass through.
- Lodging and blockage: The cells become trapped, partly blocking the vessel and, in the lungs, interfering with blood flow and oxygen exchange.
A variety of cancers can cause tumor emboli, and the pattern depends on the cancer type and its spread.
Risk Factors
- An advanced or aggressive cancer
- Cancers known to spread through the bloodstream
- Tumors that invade nearby blood vessels
- Widespread (metastatic) cancer
Diagnosis
Tumor emboli can be difficult to diagnose because they may mimic other conditions, such as blood clots in the lungs or pneumonia.
- Imaging: CT scans and other imaging assess the lungs and blood vessels and look for the cancer and its spread.
- Tests to exclude other causes: Doctors often rule out a blood clot (pulmonary embolism) and infection, which can look similar.
- Tissue findings: In some cases, the diagnosis is confirmed when tumor cells are identified in blood vessels on a sample.
Because the picture can be complex, a specialist team usually guides the evaluation.
Treatment
Treatment focuses on the underlying cancer and on supporting the affected organ.
- Cancer treatment: Therapy directed at the cancer, such as chemotherapy or other treatments, aims to reduce the tumor burden and the source of emboli.
- Supportive care: Oxygen and other measures support breathing and circulation when the lungs are involved.
- Managing complications: Care for strain on the heart and lungs or for effects in other organs.
Because tumor emboli occur in people who already have cancer, treatment is individualized and coordinated by the oncology and other specialist teams. Blood thinners, which treat ordinary blood clots, are used according to each person's situation rather than as a standard treatment for tumor emboli themselves.
Outlook and Monitoring
- The outlook depends largely on the type and stage of the underlying cancer and how it responds to treatment
- Ongoing cancer care and monitoring help detect and manage complications
- People with cancer should report new or worsening breathlessness, cough, or chest symptoms promptly
- A coordinated care team guides treatment and supportive care
When to See a Doctor
People with cancer who develop new or worsening shortness of breath, cough, chest discomfort, or fatigue should contact their care team promptly so the cause can be investigated. Seek emergency care for sudden severe shortness of breath, chest pain, fainting, or a bluish color of the lips or skin, as these can signal a serious problem with the lungs or circulation that needs immediate evaluation.
Frequently Asked Questions
What are tumor emboli?
Tumor emboli are clumps of cancer cells that break off from a tumor, travel through the bloodstream, and become lodged in smaller blood vessels, most often in the lungs. They are part of how some cancers spread and can block blood flow.
How are tumor emboli different from blood clots?
A blood clot is made of clotted blood, while a tumor embolus is made of cancer cells. Both can block vessels and cause similar symptoms such as breathlessness, but they have different causes and are managed differently.
What symptoms do tumor emboli cause?
When they affect the lungs, they often cause shortness of breath, cough, chest discomfort, and low oxygen, sometimes worsening over days to weeks. If they reach other organs, symptoms reflect reduced blood flow there, along with any symptoms of the underlying cancer.
How are tumor emboli treated?
Treatment centers on treating the underlying cancer to reduce the source of the emboli, along with supportive care such as oxygen and management of complications. Care is coordinated by an oncology and specialist team and tailored to the individual.
References
- National Cancer Institute (NCI). Metastatic Cancer.
- MedlinePlus, U.S. National Library of Medicine. Metastatic cancer.
- American Cancer Society. How Cancer Spreads.