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What Are the Symptoms of Thymus Cancer?

Older man showing signs of fatigue
Unexplained shortness of breath is one possible symptom of thymus cancer.

People with thymic tumors usually do not have symptoms until the tumor is big enough to press against air passages and blood vessels in the area of the thymus, or against the ribcage or breastbone. Here are some symptoms you might have if this happens:

  • If the tumor presses against the trachea (windpipe), you may have shortness of breath.

  • If the tumor presses against the veins that carry blood from your head and neck to your heart, your face or arms, or both, may swell.

  • You may develop pain in your chest, particularly behind your breastbone.

  • Rarely, swallowing can be difficult because of a growth or bleeding into the tumor.

Although these are some symptoms of thymus cancer, they may also be caused by other, less serious medical problems. If you have any of these symptoms, talk with your doctor.

Associated syndromes

You may also have symptoms that are not related to pressure caused by the tumor. These are called associated syndromes. These syndromes are usually caused by what the tumor makes (such as hormones and immune products), rather than by the tumor itself. The syndromes can appear when the tumor is in the very early stages. They are important in the early diagnosis of thymus cancer.

These are the associated syndromes linked to thymus cancer:

  • Myasthenia gravis. This is an autoimmune disease that can cause severe muscle weakness. The areas affected most often are the eyes, neck, throat, and chest. This can cause blurred or double vision, difficulty keeping the eyes open or looking upwards. It may also lead to trouble swallowing and breathing. You may also have serious fatigue that usually gets worse as the day goes on. While 30 to 50 percent of patients with thymomas also have myasthenia gravis, all people who have myasthenia gravis do not have thymus cancer. While the thymus is abnormal in 70 percent of people with myasthenia gravis, only a small percentage (about 15 percent) of these have thymomas.

  • Red cell aplasia. This is when the bone marrow does not make enough red blood cells. Red blood cells carry oxygen from the lungs to other body tissues. When your body doesn't make enough red blood cells, you have a low red blood cell count, a condition called anemia. Anemia may cause weakness, dizziness, shortness of breath, and fatigue. About 5 percent of patients with thymomas experience this. 

  • Hypogammaglobulinemia. This is when the body does not make enough infection-fighting antibodies. This can make you more likely to get infections. About 10 percent of people with hypogammaglobulinemia also have thymomas (known as Good’s syndrome).

If you have any one of these syndromes, you should talk to your doctor about getting checked for a thymic tumor.