Causes | Types | Symptoms | Diagnosis | Treatment | Outlook | Next Steps
Thymus cancer is a rare condition involving abnormal growths on the thymus gland, a small organ that is a part of the immune system. Multiple types of treatment are available when detected early. If left untreated, thymus cancer can spread to other parts of the body and become fatal.
- There are two main types of thymus cancer tumors. The most common, thymomas, grows slowly and rarely spreads beyond the thymus. The other type, thymic carcinomas, grows faster and is more likely to spread to other parts of the body.
- The thymus gland is located in the middle of the chest, which can cause tumors to press on nearby structures and lead to symptoms such as shortness of breath, chest pain, and weight loss. Thymus cancer can also coincide with a variety of autoimmune conditions.
- Surgery is the most common form of treatment for thymus cancer. Occasionally, other treatments may also be used, such as chemotherapy or radiation therapy, especially if the entire tumor cannot be removed.
What causes thymus cancer is still not entirely understood. Like other forms of cancer, it begins when DNA changes (also known as mutations) occur that make the thymus cells divide and grow at an abnormal rate. However, researchers are still investigating the specific way this happens and the reasons why it affects some people and not others.
The following are the only known risk factors for thymus cancer:
- Age: Thymus cancer is most common in adults older than 70. It is relatively rare in children and young adults.
- Ethnicity: Asians, Pacific Islanders, and African Americans are more prone to thymus cancer, while whites and Latinos are less prone.
There are two main types of thymus cancer tumors. Although both form in the thymus gland, they act differently:
- Thymomas: This type of cancer resembles the normal cells of the thymus. While it is the most common type of thymus cancer, it grows slowly and rarely spreads beyond the thymus.
- Thymic Carcinomas: This cancer does not look like normal thymus cells. It also grows quickly and is more likely to spread beyond the thymus, making it more difficult to treat.
In its early stages, thymus cancer does not typically present any symptoms. However, because the thymus is located in the middle of the chest, symptoms may develop as the tumor grows and presses against airways, blood vessels, and other nearby structures.
The following are some possible symptoms:
- Chest pain
- Decreased appetite
- Difficulty swallowing
- Shortness of breath
- Swelling in the face, neck, or upper chest
- Weight loss
Related Autoimmune Diseases
Patients with thymus cancer often develop autoimmune diseases that are related but not directly caused by the cancer. Known as autoimmune paraneoplastic diseases, they cause the immune system to attack the body itself. While it is not known exactly why these diseases develop alongside thymus cancer, a possible explanation is that the tumor interferes with how the thymus regulates the immune system.
The following are the most common autoimmune paraneoplastic diseases linked with thymus cancer:
- Myasthenia Gravis: This condition causes the immune system to block the signals for muscle movement, leading to decreased muscle strength, blurry vision, and shortness of breath. It is the most common disease associated with thymus cancer.
- Red Cell Aplasia: Patients with this condition have a diminished ability to produce new red blood cells, which carry oxygen throughout the body. This can lead to weakness, exhaustion, dizziness, and shortness of breath.
- Hypogammaglobulinemia: This condition inhibits the body’s ability to produce antibodies, which are vital to fighting infection, leaving patients more susceptible to disease.
The first step to diagnosing thymus cancer is typically a physical examination. Doctors will check the body for any possible symptoms or signs of the disease, such as unusual lumps or swelling. They will also examine the patient’s medical history. If thymus cancer is suspected, additional tests will be required. These may include the following:
- Blood Tests: While not specifically used to diagnose thymus cancer, blood tests can confirm the presence of autoimmune conditions such as myasthenia gravis. They may also be used to make sure a tumor isn’t a part of the thyroid.
- Imaging Tests: These form an image of your thymus and the surrounding area so that doctors can confirm a diagnosis and learn more about the tumor’s characteristics. These tests may include a chest x-ray, a computerized tomography (CT) scan, a magnetic resonance imaging (MRI), and a positron emission tomography (PET) scan.
- Biopsy: This is a surgical procedure that removes a tiny portion of tissue so that doctors can examine it under a microscope to check for signs of cancer.
If a diagnosis is confirmed, doctors will classify (or stage) the tumor according to its size, location, and how far it has spread. Determining the cancer’s stage is an essential step for planning how to treat it. The following are the stages used for thymus cancer:
- Stage I: Cancer cells can only be found in the thymus itself.
- Stage II: Cancer cells can be found in the thymus and in the surrounding fat or chest cavity lining.
- Stage III: Cancer cells have spread beyond the thymus and into nearby organs, such as the lungs or large blood vessels leading to the heart.
- Stage IVA: Cancer cells have spread across both the heart and the lungs.
- Stage IVB: Cancer cells have spread into either the blood or lymphatic systems.
There are multiple types of treatment available for thymus cancer. Doctors will determine which is best based on several factors, such as the type of tumor (thymoma or thymic carcinoma), its stage, and the patient’s general health.
The following are the most common types of treatment for thymus cancer:
Surgical removal of the tumor is the primary form of treatment for thymus cancer. During surgery, an incision is made down the center of the chest and the breast bone (sternum) is split open, giving the surgeon full access to the thymus. Depending on the extent of the cancer, they will then remove the tumor, take out the entire thymus gland (a procedure called a thymectomy), and/or remove parts of nearby organs where the tumor has spread.
This form of treatment kills cancer cells by directing high-energy x-rays and other forms of radiation at them. This radiation can either be administered externally using a machine, or internally by placing a radioactive substance onto or near the tumor. Radiation therapy is often used alongside surgery to kill off any remaining cancer cells and reduce the risk of recurrence.
Chemotherapy uses medicine (often a combination of different types of medicines) to damage and destroy cancer cells. In systemic chemotherapy, these drugs travel through the bloodstream and attack cancer cells throughout the body instead of in just one specific area. This makes it a good option for cancer that has spread (metastasized) beyond the original tumor. Chemotherapy treatments are typically administered in four to six cycles and can last several weeks.
Hormone therapy removes or blocks specific hormones that are responsible for cancer cell growth. Although hormones are produced by the thyroid and other glands to regulate certain body functions, tests may show that the cancer cells have the ability to grow by receiving or attaching onto some hormones. If this is the case, hormone therapy will use drugs such as corticosteroids to lower the production or stop the effectiveness of those hormones altogether.
This treatment uses the body’s own immune system to fight cancer. Because cancer often develops from normal cells, the immune system may not recognize it as something it should remove. Immunotherapy solves this by helping the immune system find the cancer, then slow or stop it from spreading.
Successfully treating thymus cancer will depend on a variety of factors, such as the stage of the cancer, any underlying conditions, and the overall health of the patient.
Data from the American Cancer Society divides the five-year survival rates for thymus cancer into three general categories depending on if the cancer is only in the thymus (localized), has spread to nearby organs or lymph nodes (regional), or has spread throughout the body (distant):
- Localized: 95 percent
- Regional: 78 percent
- Distant: 38 percent
As part of a world-class medical center, the Thymus Program at Columbia offers patients access to the most comprehensive care possible. We offer innovative new approaches, such as the latest minimally invasive treatments, alongside a multidisciplinary and experienced team with unmatched surgical skill. Our doctors have helped develop some of the most effective treatments for thymus cancer and related diseases, and continue to collaborate with specialists across a variety of fields in order to give each patient the best care possible. Whether you are seeking a diagnosis or need immediate treatment, we will help get you back on the road to health.
Call us at (212) 305-3408 to speak to our team, or use our online form to schedule an appointment.