Thymoma is an unusual cancer associated with several diseases related to the immune system. We specialize in robotic thymectomy, using the da Vinci surgical robot for our thymoma surgery. With three tiny incisions in the right chest, we perform a complete removal of the thymus.
What is Thymoma?
Thymoma is an unusual cancer originating in the epithelial cells of the thymus but it is the most common cancer of the anterior mediastinum, the area just in front of the heart, or just below the sternum (breast bone). The thymus is considered a gland that is very important in the development of a special cell involved in body defense and cancer surveillance, the T-lymphocyte. Although very active in childhood, the thymus decreases in size and function and is replaced by fatty tissue.
Thymomas are associated with several diseases related to the immune system. The most common, affecting between one-quarter and one- third of all thymoma patients is myasthenia gravis. Thymomas are also associated with aplastic anemia (low red blood cell count) and hypogammaglobulinemia (low levels of antibodies) among other less common diseases. A lesser- known and less understood association is with secondary cancer. Up to 15 percent of patients with thymoma have a secondary extrathymic cancer during their lifetime. There are no known risk factors that cause the development of thymoma.
Classification
There are two commonly used classifications of thymoma. The WHO (World Health Organization) classification is based on the histologic characteristic of the thymoma. Tumors are classified as A, AB, B1, B2, and B3 depending on the architecture and the similarity with a healthy thymus. The Masaoka classification describes the extension of the disease and is the most commonly used staging system. Tumors are classified as:
This classification is important in tailoring treatment for each individual patient. For example, patients with Stage III Thymoma may need pre-operative treatment with radiation therapy and/or chemotherapy.
Presentation
Thymomas are more common in the fourth to fifth decade of life and there is no sexual predilection. Although development of a thymoma in childhood is rare, children are more likely than adults to have symptoms. Of patients with a thymoma, one-third to one-half do not have any symptoms associated with the disease, and one-third of patients present with local symptoms related to the tumor encroaching on surrounding structures. Cough and chest pain are the most common symptoms, but swelling of the face and upper body (superior vena cava syndrome), difficulty swallowing (dysphagia), and hoarseness may also occur. One-third of patients are found by chance during an examination for myasthenia gravis.
Diagnosis
Thymomas can be diagnosed with computerized images of sections (tomography) of the chest. They are typically located in the anterior mediastinum behind the sternum (breastbone). A needle biopsy can be done to confirm the diagnosis of thymoma, but many surgeons prefer not to do it for fear of spreading cancer cells in the needle track. This fear is not corroborated by scientific evidence, but a needle biopsy is usually reserved for more advanced tumors when a concern exists for invasion of surrounding structures. Occasionally magnetic resonance of the chest is used to investigate anterior mediastinal masses and investigate invasion of surrounding structures. PET CT (positron emission tomography) is a test that may show areas of malignant cells in the whole body and is occasionally used in the diagnosis of thymomas.
Treatment
Thymomas are best treated with complete removal of the tumor and the thymus. A complete resection of the tumor and thymus is very important and prevents recurrence of the disease. Although often recommended, the use of postoperative radiation therapy is controversial. Our studies have not shown significant effects of postoperative radiation therapy in Stage II Thymoma. Patients with Stage III Thymoma may have a lower recurrence rate if treated with postoperative radiation therapy.
Surgical Options
We use the da Vinci surgical robot for our thymoma surgery. The robot allows us to complete the operation with three one-inch incisions, usually in the right chest, performing a complete removal of the thymus. Using the surgical robot three-dimensional vision and articulating mini wrists, we can perform a complete minimally invasive resection of the tumor and the thymus. Our work shows that robotic thymectomy is superior to transsternal thymectomy, decreasing blood loss, hospital stay and complications. Most patients are discharged the next day of their surgery and usually resume normal activities in one-to-two weeks.
Large tumors or those invading other structures may require traditional surgery through the sternum to allow a complete removal of the tumor.
Prognosis
Patients with early stage (I and II) disease have a very good prognosis when the tumor is completely resected. Patient with stage III and IV have a worse prognosis, but relatively long survival can be expected with treatment.