What is Thymoma?

A type of rare cancer that develops on a gland called the thymus is known as thymomas and thymic carcinomas. Thymomas usually do not cause symptoms in their early stages, but when they occur may include the following symptoms. For example, chest pressure or pain. While the primary treatment is surgery, it may also involve clinical trials.

A gland located behind the breastbone is called the thymus, and it plays an important role in the development of white blood cells that fight against infections. These cells are also known as T-lymphocytes (T-cells).

This gland consists of 2 types of cells, including epithelial cells and lymphocytes. However, each type of cell may turn into cancer. For example:

Abnormal epithelial cell growth often leads to thymoma and thymic carcinoma.
Abnormal lymphocyte growth commonly causes Hodgkin or non-Hodgkin lymphoma.

Thymic carcinomas and thymomas are also called thymic epithelial tumors (TETs).

What is the Difference between Thymoma and Thymic Carcinoma?

While both types of this cancer are thymic epithelial tumors (TETs), there are some important differences. For example:

In most cases, thymomas grow slowly and do not tend to spread to other structures and organs in the body.
Thymic carcinoma usually develops faster than thymomas and is more prone to metastasize (spread to other parts of the body).

Generally, treatments for people with this type of cancer are different because they depend on several conditions. These include the size, location, and severity of the cancer, overall health, age, and preferences.

Generally, this is a rare type of cancer that affects about 400 people each year in the United States.

Symptoms

This type of cancer usually does not cause any symptoms in the early stages. However, the symptoms may appear due to the tumor that puts pressure on the organs in the chest. Usually, other symptoms that people with thymoma experience are associated with paraneoplastic syndromes.

Primary Symptoms

These include:

Persistent cough
Chest pain
Shortness of breath
Swallowing problems

Sometimes, tumors may squeeze or block large veins that carry blood to the heart (vena cava), which may lead to a life-threatening condition known as superior vena cava syndrome. When it occurs, people usually experience the following symptoms. For example:

Cough
Breathing problems
Swelling in the neck, face, arms, and hands
Visible veins in the upper part of the body
Headaches
Dizziness
Extreme tiredness (fatigue)

Paraneoplastic Syndromes Symptoms

People with thymomas may experience some symptoms associated with paraneoplastic syndromes. These include:

Drooping eyelids, fatigue, muscle weakness, and double vision are often noticed in people with myasthenia gravis
Anemia (pure red blood cell aplasia)
Frequent infections, diarrhea, and swollen lymph nodes (hypogammaglobulinemia)

Causes

Experts do not fully understand why thymomas and thymic carcinomas happen. However, research is ongoing to determine connections to heredity, viruses, and other cancers.

Risk Factors

This cancer is mostly diagnosed in adults from 40 to 75 years old. Most of them in the United States have Pacific Islander or Asian heritage.

In most cases, paraneoplastic syndromes are associated with thymoma. When a person develops an autoimmune paraneoplastic syndrome, his/her body’s immune cells begin to attack healthy cells mistakenly, which may lead to symptoms. Check below the most common paraneoplastic syndromes associated with thymoma:

Myasthenia gravis – This autoimmune condition often affects the nerves and muscles.
Pure red cell aplasia (PRCA) – This is a blood disorder in which the bone marrow does not produce enough red blood cells.
Hypogammaglobulinemia (Good syndrome) – This is also an autoimmune condition where the immune system does not produce enough antibodies to fight infections.

In addition, there are other paraneoplastic syndromes that are less commonly associated with thymomas. For example:

Rheumatoid arthritis
Thyroiditis
Sjogren syndrome
Polymyositis
Lupus erythematosus

Diagnosis

Physicians usually identify the tumor during examinations done for other reasons. After that, they may perform a physical examination to check for abnormalities linked to the cancer and ask some questions about the symptoms and medical history. Usually, to confirm a thymoma, doctors perform the following tests. Examples include:

Chest X-ray – This is an imaging test used to see masses (tumors) inside the body.
CT (computerized tomography) scans – This is one of the most common imaging tests used to confirm thymomas. Usually, doctors inject a dye into a vein because it helps get clearer images during a CT scan. In some cases, this is the only test needed to confirm the cancer.
MRI (magnetic resonance imaging) scans – This imaging test is used to get more detailed images of the thymus and nearby organs. It uses a magnetic field and radio waves to produce pictures.
PET (positron emission tomography) scans – This test involves injecting a small amount of radioactive material into the veins, which makes tumors show up more clearly on imaging. In some cases, doctors may perform a PET and CT scan at the same time.
Biopsy – This is one of the most common tests used to confirm thymomas. It involves the removal of a small sample of the tumor for testing in the laboratory under a microscope. It is done to check for cancerous cells.

Additionally, once you are diagnosed with thymoma, physicians may perform additional tests to determine the extent (stage) of the cancer. In most cases, they perform imaging tests.

Treatment

Healthcare professionals usually recommend different treatments for people with this type of cancer. It depends on several factors, including your age and preferences, the type and exact location of the tumor, and existing health problems. Check below the most common treatments recommended by doctors for people who develop a thymoma:

Surgery – Commonly, this is the primary treatment for people with thymoma that has not spread. During this procedure, surgeons may also remove nearby lymph nodes to make sure there are no remaining cancerous cells. However, it is not possible to remove the whole tumor safely.
Radiation therapy – This is a cancer treatment that involves powerful energy beams to destroy cancerous cells. This energy often comes from protons, X-rays, or other sources. Usually, doctors recommend external beam radiation therapy for people with thymomas. Furthermore, doctors may also recommend chemotherapy or surgery along with radiation therapy.
Chemotherapy – This treatment involves strong medicines that destroy cancerous cells throughout the body. While this treatment can be prescribed along with radiation therapy to improve its effectiveness, doctors may recommend it before or after surgery. It is prescribed before surgery to shrink a large tumor or after surgery to destroy the cancer cells that may remain even after the removal of the tumor.

Other Treatments

Targeted therapy – This treatment uses medicines that target a specific protein in the cancer cells, causing them to die. In most cases, doctors prescribe targeted therapy when previous treatments do not work.
Immunotherapy – This is another option used when other treatments do not work. It also involves medicines that boost the immune system to find and kill cancerous cells. Commonly, malignant (cancerous) cells produce some chemicals that help them hide from the immune system. Immunotherapy helps boost the immune system.
Clinical trial – This treatment involves a study in which doctors determine the effectiveness of new or different cancer treatments.

Frequently Asked Questions

What is the survival rate for thymoma and thymic carcinoma?

Commonly, thymomas are associated with a better prognosis compared to thymic carcinoma, and the survival rate is better when the cancer has not spread. Check below the 5-year survival rates when the cancer has not spread:

The cancer is only in the thymus (95%)
It spreads to nearby organs and lymph nodes (78%)
The cancer spreads to other parts of the body, also known as metastatic cancer (38%)

Usually, the survival rate depends on multiple factors. For more details, discuss it with your physician.

Is thymoma cancer curable?

Yes, but only in its early stages. It means the tumor is localized in the thymus and has not spread to other parts of the body.

What are the symptoms of having a thymoma?