What Are Thymoma and Thymic Carcinoma?

Medically Reviewed by Sabrina Felson, MD on February 21, 2024
4 min read

Thymoma and thymic carcinoma are two types of thymus cancer. The thymus is a small organ in the upper chest. It’s in front of and above the heart. It makes white blood cells that help your body fight infection.

With these types of cancer, tumors form on the outside of the thymus. Both kinds are rare. Between the two, there are about 400 cases each year in the United States. Generally, thymoma is less serious than thymic carcinoma. It’s also easier to treat.

With thymoma, the tumor cells don’t look much different than the regular (non-cancerous) thymus cells. They grow slowly and they don’t usually spread to other places in the body. People with thymoma often have autoimmune diseases like myasthenia gravis and acquired pure red cell aplasia too. With these conditions, your body attacks its own healthy tissues and organs.

With thymic carcinoma, the tumor cells do not look like normal thymus cells. They grow more quickly. By the time the cancer is found, it often has spread to other areas. That makes it harder to treat.

Doctors aren’t sure what causes thymoma and thymic carcinoma. These cancers don’t seem to run in families. The conditions affect both men and women. The chance of getting them is higher for older people. African-Americans have a higher chance than white people. They’re usually found almost by chance, when doctors are using X-rays or CT scans to look for something else.

Check with your doctor if you have these common symptoms of thymoma and thymic carcinoma:

In rare cases, a tumor from thymus cancer will press on a major blood vessel that takes blood to the heart. This is called superior vena cava syndrome, or SVCS. It can cause problems like a swollen neck, chest, and face or swollen veins in your upper body. It can also show up as headaches and dizziness. This is serious. If you think you might have it, you need medical help right away.

There is no single test for thymus cancers. During an examination, your doctor will look for signs and symptoms of the disease, ask how you feel, and check your family health history. They may refer you to an oncologist (cancer doctor).

These are tests your doctor might use:

  • X-ray
  • CT scan -- uses X-rays and a computer to see inside your body
  • MRI -- uses radio waves, a magnet, and a computer to take detailed pictures inside your body
  • PET scan -- uses a small amount of radioactive glucose (sugar) to look for cancer cells

If there is a suspicious mass detected, your doctor will do a biopsy to get a tissue sample. It’s typically removed with a needle and then studied under a microscope. If you have thymus cancer, your doctor will find out if it’s spread to other parts of your body.

It depends on a number of things, like your general health and whether this is the first time you’ve had either type of cancer, and if the cancer has spread. Thymic carcinoma often comes back. It’s less likely with thymomas.

Your doctor will talk with you about the best way to treat your cancer. Some people get a second opinion. This means going to another doctor to see if they would treat it differently.

The most common types of treatment:

  • Surgery to remove the tumor is an option.
  • Radiation can be used to kill cancer cells before or after surgery.
  • Hormone therapy blocks hormones to stop cancer cells from growing.
  • Chemotherapy uses medicines to stop cancer cells from growing. Sometimes a combination of medications is used.

Doctors sometimes try new ways to treat thymoma and thymic carcinoma. These are called clinical trials. Ask your doctor if it makes sense for you to be part of one of these trials.

After treatment, your doctor will want you to be tested from time to time to make sure you’re doing well and the cancer hasn’t come back. This could be every few months for a couple of years.

Cancer is hard. You might feel worried about your health, the future, the cost of treatment, work, and family. You’re not alone -- these are common feelings. Your health care team can put you in touch with someone to help you create a “survivorship plan.” It’s a way for people who have had cancer to move forward and stay as positive and healthy as possible.