Pituitary gland
tumours

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What is a pituitary gland tumour?

Pituitary gland tumours start in cells of the pituitary gland. They are considered non-cancerous, or benign, at diagnosis. If a pituitary gland tumour grows into surrounding tissues or spreads (metastasizes) to other parts of the body, it is then considered cancerous, or malignant.

The pituitary gland is a small, oval-shaped gland inside your head at the base of your brain. It is part of your body’s endocrine system. The endocrine system is the group of glands and cells that make and release hormones into the blood. These hormones control many body functions, such as growth, reproduction, sleep, hunger and metabolism. The pituitary gland makes hormones that control the activity of most other endocrine glands in the body by telling them when to make and release different hormones.

Cells in the pituitary gland sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous tumours such as pituitary adenomas. More than 99% of pituitary gland tumours are non-cancerous, but they can still have serious effects. Some tumours can cause vision problems because of where they are in the brain. Most pituitary adenomas are functioning. This means that they make pituitary hormones. Functioning tumours can cause different problems depending on the hormones they release.

In rare cases, changes to cells in the pituitary gland can cause cancer. This type of cancer is called pituitary carcinoma.

Other types of cancer can spread to the pituitary gland, but this is not the same disease as cancer that starts in the pituitary gland. Cancer that starts in another part of the body and spreads to the pituitary gland is called pituitary gland metastasis. It is more common than cancer that starts in the pituitary gland. Breast and lung cancers are the most common cancers that spread to the pituitary gland.

Diagram of location of the pituitary

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