Thymus Gland Cancer Overview

The thymus is a soft gland with two lobes located in the mediastinum above the heart. It is large in infants and children but shrinks after puberty and is smaller in adults. It plays an important role in the development of the immune system. The thymus produces the hormone thymosin which helps T lymphocytes, also called T cells, mature. Once mature, T cells are able to recognize and attack foreign organisms that are harmful to the body. They are distributed by the blood and lymphatic tissues throughout the body.

Cancer begins when normal cells change and grow with no control. This growth creates a mass called a tumor. A tumor can be noncancerous or cancerous. If cancerous, it can spread to other parts of the body (metastatic cancer). The thymus contains two main types of cells called epithelial cells and lymphocytes. Thymic epithelial cells are the cells that line the thymus gland. When these cells become abnormal and start to grow without control, thymoma and thymic carcinoma starts. Cancer of the thymus is rare type of cancer. Other tumor types can develop in the thymus. They include lymphomas, germ cell tumors, carcinoid tumors, carcinomas, and thymolipomas. These types of tumors are very uncommon.   

A risk factor is anything that increases a person’s chance of developing a specific cancer.  Thymoma usually occurs in people between the ages for forty and sixty. However, there are no specific risk factors for thymoma. 

At first, people with thymoma may have no signs or symptoms of the cancer. As the cancerous tumor grows, people with thymoma may experience a persistent cough, shortness of breath, difficulty swallowing, and chest pain.  These symptoms happen if the tumor presses on organs in the chest area.  If the tumor grows very large, it may cause swelling on the neck and face. This happens because the tumor may be pressing on the superior vena cava in the chest. The superior vena cava is the second largest vein in the human body.    

Some people with thymoma also have myasthenia gravis.  Myasthenia gravis is an autoimmune disorder. It is caused by antibodies or T-cells that attack molecules, cells, or tissues of the person producing them.  The main symptom of myasthenia gravis is weakness in different muscles of the body.  The disorder may affect any muscle that can be controllled, such as those that control eye movements, chewing, swallowing, coughing, and facial expression. Muscles that control breathing and movements of the arms and legs may also be affected.

People with thymoma may also have other syndromes.  Patients can have severe low red blood cell count or severe anemia, called pure red cell aplasia, or a low gamma globulin level.

The treatment options for malignant thymoma can vary depending on your overall health and how advanced the cancer is. Some treatments are standard of care which is the currently used treatment for this type of cancer. Standard of care might include surgery. A surgical operation to remove a thymoma is called a thymectomy.  Radiation, chemotherapy, surgery or a combination of these treatments may be used to treat thymoma. Patients may also have the option to be treated on a clinical trial which is meant to help improve current treatments (standard of care) or obtain information on new treatments for patients with malignant thymoma. It is important to discuss your treatment options with your treatment team which usually consists of oncologic surgeons, radiation oncologist, and medical oncologists.  They will work with you to determine which treatment is right for you.