Pituitary Gland Tumor: Overview

Approved by the Cancer.Net Editorial Board, 11/2014

ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Pituitary Gland Tumor. To see other pages, use the menu on the side of your screen. Think of that menu as a roadmap to this full guide.

About the pituitary gland

The pituitary gland is a small gland located near lower part of the brain. This gland is often referred to as the “master gland” because it releases hormones that affect many bodily functions and because of its influence on the body’s other glands. The pituitary gland is controlled by the hypothalamus, a small structure which is part of the brain that is connected to the pituitary gland. A pituitary gland has two lobes, the anterior, or front, and the posterior, or back. Each lobe is responsible for releasing specific hormones. These different hormones include:

Anterior pituitary lobe hormones

  • Thyroid stimulating hormone (TSH) stimulates the thyroid gland, which helps regulate the body’s metabolism

  • Adrenocorticotrophic hormone (ACTH) controls the hormones released by the adrenal gland that support blood pressure, metabolism, and the body's responses to stress

  • Gonadotropins, a family of hormones that include follicle stimulating hormone (FSH) and luteinizing hormone (LH), stimulate production of sperm in a man’s testicles or eggs in a woman’s ovaries, and regulate a woman's menstrual cycle

  • Growth hormone promotes growth of the long bones in the arms and legs, thickens the skull and bones of the spine, and causes the tissue over the bones to thicken. It also regulates body composition and bone density, as well as affects a number of different processes in adults

  • Prolactin stimulates milk production in women after childbirth

  • Lipotropin stimulates the movement of fat from the body to the bloodstream

  • Melanocyte stimulating hormone (MSH) regulates the production of melanin, the pigment in skin

Posterior pituitary lobe hormones

  • Oxytocin stimulates contraction of the uterus during childbirth and the flow of milk during breastfeeding. This hormone may also be important in forming attachments in relationships of all types

  • Antidiuretic hormone, also known as vasopressin, increases reabsorption of water by the kidneys and allows a person to stay hydrated

Tumors in the pituitary gland

Cancer begins when healthy cells change and grow uncontrollably, forming a mass called a tumor. A pituitary gland tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread beyond the pituitary gland. A benign tumor means the tumor can grow but will not spread. Most often, pituitary gland tumors are noncancerous growths called pituitary adenomas. However, a pituitary gland tumor can very rarely act like a cancerous tumor by spreading to other parts of the brain or the body.  While some pituitary tumors invade parts of the body nearby, they are not considered to be cancerous even though this definition would be considered malignant in other types of tumors.

Pituitary gland tumors are NOT brain tumors, as the pituitary gland is located under the brain and is separate from the brain. Pituitary gland tumors are tumors of an endocrine gland.  Tumors in this gland can be very serious because a pituitary gland that does not work can cause problems with other glands and other organ systems. This is because the tumor starts in cells that make hormones, so the tumor itself can make too many hormones and cause significant problems. This is called a “functional” tumor. The tumor can also cause the gland to produce too few hormones. If the tumor presses on nearby structures, such as the optic nerves in the eye, it can limit a person’s sight. To learn more general information about tumors that affect hormones, visit the Cancer.Net Guide to Endocrine Tumors.

The next section in this guide is Statistics and it helps explain how many people are diagnosed with this disease and general survival rates. Or, use the menu on the side of your screen to choose another section to continue reading this guide.