Thymomas and thymic carcinomas are rare cancers that form on a gland called your thymus. Usually, they don’t cause symptoms at first. When symptoms are present, they may include chest pressure or pain. Treatments range from surgery to clinical trials.
Thymoma and thymic carcinoma are forms of cancer that start in a gland called your thymus. Your thymus is located behind your breastbone. It plays an essential role in the development of white blood cells that fight infection called T-lymphocytes (T-cells).
Your thymus consists of two cell types: epithelial cells and lymphocytes. Either type can grow abnormally and transform into cancer:
Thymoma and thymic carcinoma are also called thymic epithelial tumors (TETs) because they start in your thymus and originate from epithelial cells.
Thymomas and thymic carcinoma are both thymic epithelial tumors (TETs), but there are some important differences:
The treatments your healthcare provider prescribes and your prognosis depend on whether you have thymoma (less aggressive) or thymic carcinoma (more aggressive).
Thymomas and thymic carcinoma are most common in adults between 40 and 75. Most people diagnosed in the U.S. have Asian or Pacific Islander heritage.
Autoimmune paraneoplastic syndromes are commonly associated with thymoma. If you have an autoimmune paraneoplastic syndrome, your body’s immune cells mistakenly attack healthy cells, causing unpleasant symptoms. The most common paraneoplastic syndromes associated with thymoma are:
Other paraneoplastic syndromes associated with thymomas appear less often. They include:
Thymoma and thymic carcinoma are the most frequently occurring tumors you get in your thymus. Still, they’re rare overall. Only about 400 people in the U.S. are diagnosed each year.
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Most people don’t have symptoms in the early stages. Instead, symptoms often arise when a tumor impacts organs in your chest. Other symptoms are associated with paraneoplastic syndromes.
Pain and breathing issues may be signs of thymoma or thymic carcinoma. Symptoms include:
Tumors can block or squeeze the large veins that carry blood to your heart, called the vena cava. Compression of the vena cava can cause a very serious condition known as superior vena cava syndrome. If this happens, you may experience symptoms that include:
If you have a thymoma, you may notice signs and symptoms of one or more paraneoplastic syndromes, including:
There are no known genetic or environmental risk factors for thymoma. Research is ongoing to look for links to viruses, heredity and other cancers.
Your healthcare provider may discover you have a tumor after performing imaging to explore what’s causing your symptoms.
To make a diagnosis, your healthcare provider will perform a physical exam and ask about your symptoms and medical history. They may perform any of the following procedures to get more information about your tumor:
Cancer staging classifies cancer based on how serious it is. Many factors determine disease severity. Your cancer’s stage helps your healthcare provider plan treatments and predict likely outcomes.
Thymomas and thymic carcinoma are staged using the TNM system. TNM stands for tumor, lymph nodes and metastasis. To stage your cancer, healthcare providers ask questions like:
Your healthcare provider will use the answers to these questions to stage your cancer from I to IV. Increasing numbers mean more cancer spread. For example, stage I cancer hasn’t spread as much as stage IV cancer.
Your provider may consider other factors, like how abnormal the cancer cells are, to determine your condition’s seriousness.
Your treatment will depend on various factors, including the type of cancer you have and your cancer stage. Other factors include whether the cancer’s newly diagnosed or if it went away and then returned (recurred).
Your healthcare provider may recommend that you work with a palliative care team to support you throughout your cancer diagnosis. Palliative care professionals include doctors, nurses and other care specialists who can help you manage cancer symptoms and treatment side effects. Palliative care is an excellent resource, no matter your cancer stage or prognosis.
Generally, thymoma is associated with a better prognosis than thymic carcinoma. Also, cancer only in your thymus is associated with a better survival rate than cancer that’s spread. The five-year survival rates for cancers in your thymus are as follows:
Still, these numbers don’t consider specifics like your overall health, type of cancer, cancer stage or response to treatment. Your survival rate depends on multiple factors that your healthcare provider can explain.
In some cases, all signs and symptoms of the cancer disappear (remission), and the cancer doesn’t return. However, often, both types recur. With thymoma, you may go longer without the cancer returning. You’ll still need to visit your healthcare provider regularly to ensure you’re cancer-free.
Discuss your diagnosis and treatment options with your care team. Don’t hesitate to ask your healthcare provider any questions you have about the cancer itself or what it means for your life moving forward. Questions might include:
A note from Cleveland Clinic
A thymoma or thymic carcinoma diagnosis can mean many things. Some tumors are slow-growing, while others are more aggressive. Some can be removed completely with surgery, while others have already spread by the time your healthcare provider diagnoses you. Ask your provider about how your cancer will determine your outcomes. Discuss the benefits and risks associated with all potential treatment options.
Last reviewed by a Cleveland Clinic medical professional on 11/08/2022.
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