Pituitary Cancer Introduction
People with pituitary tumors now have more treatment choices than ever before. Doctors keep finding new treatments for pituitary tumors and ways to help people with them live better lives. We are continually learning more about pituitary tumors and their detection and treatment.
About the pituitary gland
The pituitary gland is a small gland located behind the nasal sinuses and above the roof of the mouth at the base of the skull. It connects to the hypothalamus, a part of the brain. Together, the two control the production of many of the important hormones in the body.
The pituitary gland sits in a tight bony space and has little room to grow or expand when swollen or if there is a tumor.
The pituitary gland regulates the activity of most of the glands in the body, including the adrenal and thyroid glands and sexual hormone production (regulation of ovarian function in women and testicular function in men). The pituitary gland is considered to be the main control gland of the neuroendocrine system.
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The pituitary gland has two parts--the posterior pituitary (back part) and the anterior pituitary (front part). The back part (posterior pituitary) makes the hormones called vasopressin and oxytocin:
Vasopressin. This hormone allows the kidneys to retain water and not lose it all in urine. It can increase blood pressure. It is also called ADH (for antidiuretic hormone).
Oxytocin. This female hormone helps the uterus to contract during childbirth and helps the breasts release milk when a woman is nursing a baby.
The front part (anterior pituitary) makes several kinds of hormones that, in turn, control other glands throughout the body:
Growth hormone. This hormone (also known as somatotropin) helps a child's body grow, especially at puberty. It also helps the liver make something called insulin-like growth factor (IGF-1). IGF-1 causes bones and other tissues to grow.
Thyroid-stimulating hormone. This hormone (known as TSH and thyrotropin) helps the thyroid gland to grow and to make and release the thyroid hormone.
Adrenocorticotropic hormone (ACTH). Stimulates the adrenal gland so that it can make certain steroid hormones.
Luteinizing hormone (LH). This regulates ovulation and menstruation in women and controls testosterone and the production of sperm in men.
Follicle-stimulating hormone (FSH). This affects the same body functions as LH does.
Prolactin. This helps make milk in the female breast. Its function in men is not clear.
What are pituitary tumors?
A pituitary tumor is a tumor that grows in the pituitary gland. Cancerous pituitary tumors (called pituitary carcinomas)are rare. Almost all pituitary tumors are benign adenomas(noncancerous). According to the American Cancer Society, about 7,000 people get them each year. Cancerous pituitary tumors are so rare that state and national cancer agencies do not keep a record of how many people get them each year. Most pituitary tumors are adenomas and very few people have died because of them.
Adenomas usually do not spread out of the pituitary gland. Still, they can greatly affect a person's health by pushing on other parts of the brain and by secreting excess amounts of hormones. Adenomas of the pituitary are grouped in different ways.
The first way is according to their size. Microadenomas are tumors that are smaller than one centimeter, which is about half an inch. Macroadenomas are tumors that are bigger than one centimeter. Microadenomas and macroadenomas can either make hormones (called functional adenomas) or not make hormones (nonfunctional or null adenomas).
The tumors are also grouped according to which kind of hormone they produce. The types for this grouping, named after the types of hormones the pituitary makes, are prolactin-producing adenomas, somatotropin-secreting adenomas, corticotropin-secreting adenomas, gonadotropin-secreting adenomas, thyrotropin-secreting adenomas, null cell adenomas, and adenomas of the mixed cell type.