The survival rate for stage 4 thymus cancer depends on how far the cancer has spread. Surgery might offer a cure if the cancer hasn’t spread too far. Otherwise, treatment may include chemotherapy and radiation.

The thymus gland is a small organ in the middle of your chest, just behind your sternum. As part of your body’s immune system, the thymus makes white blood cells to help your body fight infections.

Thymus cancer occurs when cells on the thymus gland grow uncontrollably and form a mass called a tumor. Thymus cancer is rare. Only 400 cases occur in the United States each year.

Doctors classify stages of thymus cancer from 1 to 4, with 4 being the most advanced. At stage 4, thymus cancer has spread (metastasized) to other parts of the body such as the lymph nodes, heart, or lungs.

Experts further divide stage 4 thymus cancer into two substages:

  • Stage 4A: Cancer has spread to nearby lymph nodes in the front chest cavity or around the lungs or heart.
  • Stage 4B: Cancer has spread to the lymph nodes deep in the chest or neck or to the inside of the lungs or other organs.

At stage 4, thymus cancer is more difficult to treat. Still, people with stage 4 thymus cancer often survive for many years after treatment.

Thymoma vs. thymic carcinoma

There are two types of thymus cancers, or thymic epithelial tumors (TETs). Though they both form in cells called thymic epithelial cells, there are key differences in the way each cancer behaves.

Thymomas typically grow slowly and don’t usually spread beyond the thymus.

Thymic carcinomas grow more quickly and are more likely to spread.

About 20% of TETs are thymic carcinomas.

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The 5-year relative survival rate measures the percentage of people with a condition who are alive 5 years after their diagnosis compared to people without that condition.

Thymus cancer is rare, so it’s difficult to measure survival rates accurately. The American Cancer Society doesn’t provide survival statistics for thymus cancer based on stage but on how far the cancer has spread.

The 5-year survival rate for thymus cancer that has spread to nearby organs or lymph nodes is 80%.

If thymus cancer has spread to distant parts of the body, such as the heart or the lungs, the 5-year survival rate drops to 38%.

Keep in mind that experts obtain these statistics using data from the past and don’t take into account the effect of new treatments.

In a recent study, researchers looked at the medical records of people with advanced thymus cancer treated between 2005 and 2015. For people with stage 3 or stage 4A thymus cancer, the 5-year overall survival rate was 60–85%, depending on which of the three chemotherapy regimens each person received.

For those with stage 4B thymus cancer, 5-year overall survival rate was between 14% and 41%.

The survival differences between chemotherapy groups were not statistically significant.

As scientists develop new treatments and evaluate them in clinical trials, we can expect survival statistics to improve.

Symptoms of stage 4 thymus cancer

When thymus cancer reaches stage 4, tumors often grow large enough to press on nearby structures, such as your esophagus or windpipe. A tumor may also get big enough to squeeze your superior vena cava, the vein that brings blood to your heart. This can cause a condition called superior vena cava syndrome.

This may cause symptoms like:

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Doctors can remove some stage 4 thymus cancers with surgery. They might also give chemotherapy before the surgery to help shrink the tumor and ease removal. This is called neoadjuvant chemotherapy.

After surgery, you may receive radiation therapy. Radiation can help destroy any tumor cells that surgery may have missed. It may also help prevent the cancer from coming back.

If your doctor doesn’t think they can remove the cancer with surgery, your treatment plan may include one or more of the following:

  • chemotherapy
  • radiation therapy
  • targeted therapy (medications that target genes that cause cancer to grow)
  • a clinical trial of an immunotherapy

A cure is possible if the surgeon can remove the entire tumor during surgery. But surgical removal isn’t always an option for stage 4 thymus cancers. Surgery is less likely to work if the cancer has spread to distant parts of your body.

Compared to thymomas, thymic carcinomas are more likely to spread and are more difficult to remove with surgery. They’re also more likely to recur (come back). Once the cancer comes back, treatments can often help manage the cancer but are unlikely to result in a cure.

Researchers are also evaluating the effectiveness of new treatments in clinical trials, which could one day lead to a cure.

Resources for support

As you navigate a cancer diagnosis, don’t hesitate to reach out for support. Your doctor or care team can refer you to a support group or counselor specializing in cancer diagnosis. You can also reach out to the following organizations:

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Stage 4 thymus cancer can be more difficult to treat than earlier stages. The cancer is also more likely to come back after treatment. Still, many people with stage 4 thymus cancer live for years after treatment.

A surgeon can try to remove as much of the tumor as possible, but chemotherapy and radiation are the main treatment options at this stage.

Since thymus cancer is rare, clinical trials of new treatments, like immunotherapies, may be a good option to improve your outlook. Ask your doctor about enrolling in a clinical trial.