Thymus cancer

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What is thymus cancer?

Thymus cancer starts in the cells of the thymus. A cancerous (malignant) tumour is a group of cancer cells that can grow into and destroy nearby tissue. It can also spread (metastasize) to other parts of the body. Cancerous tumours of the thymus are rare.

The thymus is a small gland in the top part of the chest between the lungs and under the breastbone. It makes T cells (T lymphocytes) that travel throughout the body to help fight infection, disease and foreign substances. The thymus also makes hormones and other substances to help T cells develop and keep the immune system working properly.

Diagram of the location of the thymus

Cells of the thymus sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous (benign) tumours such as thymic cysts and thymolipomas.

In some cases, changes to thymus cells can cause thymus cancer. Most often, thymus cancer starts in the epithelial cells of the thymus. These types of thymus cancer are called thymoma and thymic carcinoma.

Thymus cancer can also start in other types of cells, such as thymic neuroendocrine tumours (NETs).


A specialized organ or group of cells that produces or releases substances (such as hormones, saliva, digestive juices, sweat, tears or milk) to perform different functions in the body.


A substance that regulates specific body functions, such as metabolism, growth and reproduction.

Natural hormones are produced by glands. Artificial or synthetic hormones can be made in the lab.

immune system

The complex group of cells and organs that defend the body against infection, disease and foreign substances.

epithelial cell

A specialized cell that makes up the epithelium (a layer of cells that makes up the surface of the skin, and lines cavities, glands and passages in the body). Some epithelial cells make mucus, hormones or other secretions.

The 4 types of epithelial cells are squamous cells, columnar cells, cuboidal cells and transitional cells.


Referring to or having to do with the neuroendocrine system or the cells and organs that make up this system.