Thymoma and thymic carcinoma, also called thymic epithelial tumors (TETs), are two types of rare cancers that can form in the cells that cover the outside surface of the thymus. The thymus is a small organ that lies in the upper chest above the heart and under the breastbone. It is part of the lymph system and makes white blood cells, called lymphocytes, that help fight infection. These cancers usually form between the lungs in the front part of the chest and are sometimes found during a chest x-ray that is done for another reason.
Even though thymoma and thymic carcinoma form in the same type of cell, they act differently:
Other types of tumors, such as lymphoma or germ cell tumors, may form in the thymus, but they are not considered to be thymoma or thymic carcinoma.
Autoimmune paraneoplastic diseases are often linked with thymoma. Autoimmune paraneoplastic diseases may occur in patients with cancer but are not caused directly by cancer. Autoimmune paraneoplastic diseases are marked by signs and symptoms that develop when the body's immune system attacks not only cancer cells but also normal cells. Autoimmune paraneoplastic diseases linked with thymoma include:
Other autoimmune paraneoplastic diseases may be linked with TETs and can involve any organ.
Most patients do not have signs or symptoms when first diagnosed with thymoma or thymic carcinoma. Check with your doctor if you have any of the following:
The following tests and procedures may be used:
The prognosis and treatment options depend on the following:
The process used to find out if thymoma or thymic carcinoma has spread from the thymus to nearby areas or other parts of the body is called staging. Thymoma and thymic carcinoma may spread to the lungs, chest wall, major vessels, esophagus, or the lining around the lungs and heart. The results of tests and procedures done to diagnose thymoma or thymic carcinoma are used to help make decisions about treatment.
Cancer can spread through tissue, the lymph system, and the blood:
When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.
The metastatic tumor is the same type of cancer as the primary tumor. For example, if thymic carcinoma spreads to the bone, the cancer cells in the bone are actually thymic carcinoma cells. The disease is metastatic thymic carcinoma, not bone cancer.
In stage I, cancer is found only within the thymus. All cancer cells are inside the capsule (sac) that surrounds the thymus.
In stage II, cancer has spread through the capsule and into the fat around the thymus or into the lining of the chest cavity.
In stage III, cancer has spread to nearby organs in the chest, including the lung, the sac around the heart, or large blood vessels that carry blood to the heart.
Stage IV is divided into stage IVA and stage IVB, depending on where the cancer has spread.
The staging system used for thymomas is sometimes used for thymic carcinomas.
Recurrent thymoma and thymic carcinoma are cancers that have recurred (come back) after treatment. The cancer may come back in the thymus or in other parts of the body. Thymic carcinoma is more likely to recur than thymoma.
Different types of treatments are available for patients with thymoma and thymic carcinoma. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Surgery to remove the tumor is the most common treatment of thymoma.
After the doctor removes all the cancer that can be seen at the time of the surgery, some patients may be given radiation therapy after surgery to kill any cancer cells that are left. Treatment given after the surgery, to lower the risk that the cancer will come back, is called adjuvant therapy.
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. External radiation therapy uses a machine outside the body to send radiation toward the area of the body with cancer.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy).
Chemotherapy may be used to shrink the tumor before surgery or radiation therapy. This is called neoadjuvant chemotherapy.
Hormone therapy is a cancer treatment that removes hormones or blocks their action and stops cancer cells from growing. Hormones are substances made by glands in the body and flow through the bloodstream. Some hormones can cause certain cancers to grow. If tests show that the cancer cells have places where hormones can attach (receptors), drugs, surgery, or radiation therapy is used to reduce the production of hormones or block them from working. Hormone therapy using octreotide with or without prednisone may be used to treat thymoma or thymic carcinoma.
Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells. Tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin (mTOR) inhibitors are types of targeted therapies used in the treatment of thymoma and thymic carcinoma.
This summary section describes treatments that are being studied in clinical trials. It may not mention every new treatment being studied. Information about clinical trials is available from the NCI website.
Immunotherapy is a treatment that uses the patient’s immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body’s natural defenses against cancer. This cancer treatment is a type of biologic therapy.
For information about side effects caused by treatment for cancer, visit our Side Effects page.
For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.
Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.
Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.
Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.
Clinical trials are taking place in many parts of the country. Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.
As you go through treatment, you will have follow-up tests or check-ups. Some tests that were done to diagnose or stage the cancer may be repeated to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.
Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back).
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of stage I and stage II thymoma is surgery, which may be followed by radiation therapy.
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of stage III and stage IV thymoma that may be completely removed by surgery includes the following:
Treatment of stage III and stage IV thymoma that cannot be completely removed by surgery includes the following:
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of thymic carcinoma that may be completely removed by surgery includes the following:
Treatment of thymic carcinoma that cannot be completely removed by surgery includes the following:
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of recurrent thymoma and thymic carcinoma may include the following:
For more information from the National Cancer Institute about thymoma and thymic carcinoma, see the following:
For general cancer information and other resources from the National Cancer Institute, visit:
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PDQ® Adult Treatment Editorial Board. PDQ Thymoma and Thymic Carcinoma Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/thymoma/patient/thymoma-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389395]
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