The thymus is a small, irregular-shaped organ located in the upper chest, just behind the breastbone. A crucial component of the immune system, the thymus is responsible for the production and development of T lymphocytes, also known as T cells, a type of white blood cell that helps protect the body from a variety of infections, including those caused by fungi and viruses. Thymic carcinoma, also known as type C thymoma, is the most dangerous cancer of the thymus. This rare malignancy has a high rate of metastasis, is difficult to keep in remission, and has a poor overall prognosis.
Thymic carcinoma and other thymomas are the two main types of tumors that originate from thymic epithelial cells, which lie on the surface of the thymus and help to form its structure and shape. The World Health Organization (WHO) has created a system that physicians can use to classify any given thymoma or thymic carcinoma based on its microscopic appearance. This allows physicians to assign letters to the tumor to help identify it, develop a treatment plan, and formulate a prognosis. These letters range from A to C, with the former as the least severe, and the latter carrying the worst prognosis.
Thymic carcinoma is classified as Type C, as it is usually comprised of fast-growing cells that exhibit the most abnormalities when viewed under a microscope. At the time of diagnosis, thymic carcinoma has usually metastasized, which means that it has spread to other parts of the body. This can make formulating a treatment plan more challenging. Surgical removal of the tumor is usually the first line of therapy. Depending on the stage of the cancer at diagnosis, chemotherapy, hormone therapy, and radiation may also be prescribed. The 10-year survival rate for patients diagnosed with thymic carcinoma is approximately 28%.
Thymic carcinoma often goes unnoticed until the tumor begins to press on the patient's windpipe. It can also produce hormones that frequently cause symptoms. These may include a persistent cough, asthma, swelling of the face, diarrhea, red and warm skin, and chest pain. Some patients may have no symptoms of the cancer at all. In this case, the tumor may have been an incidental finding on a routine chest x-ray.
Thymic cancers are uncommon, representing only about 1.5% of all cancer cases. Patients most likely to be diagnosed with thymic carcinoma are men between the ages of 40 and 60. The cause of this type of cancer is unknown.