Pituitary Tumors

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Causes, Risk Factors, and Prevention TOPICS

Do we know what causes pituitary tumors?

Scientists do not know exactly what causes most pituitary tumors. During the past few years, they have made great progress in understanding how certain changes in a person’s DNA can cause cells in the pituitary to produce a tumor. DNA is the chemical in each of our cells that makes up our genes – the instructions for how our cells function. We usually look like our parents because they are the source of our DNA. However, DNA affects more than how we look.

Some genes have instructions for controlling when cells grow and divide into new cells. Genes that help cells grow and divide or cause them to live longer than they should are called oncogenes. Genes that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Tumors can be caused by DNA changes that turn on oncogenes or turn off tumor suppressor genes.

Some people inherit gene mutations (changes) from their parents that greatly increase their risk for developing certain tumors. But usually, gene mutations occur during life rather than having been inherited. These acquired mutations may result from outside exposures, such as to radiation or cancer-causing chemicals, or they may just be random events that sometimes happen when a cell divides, without having an external cause. Most pituitary tumors are not cancers, and there are no known environmental causes for these tumors.

Some of the gene mutations linked to pituitary tumors that run in families were described in the previous section, “What are the risk factors for pituitary tumors?” Members of families with these genetic syndromes can have genetic testing to find out if they are affected.

Much less is known about the causes of non-hereditary (sporadic) pituitary tumors. Some of these have acquired mutations in the AIP gene. Many growth hormone-secreting adenomas have an acquired mutation in a gene called GNAS1. These mutations are much less common in other types of pituitary adenomas.

Several other gene changes have been found in other types of pituitary adenomas, but it is not clear whether abnormal genes are always needed for pituitary tumor formation. What is known is that there is a loss of the regulatory mechanism that normally keeps the pituitary cells from growing and making too much hormone.

Because there are no known lifestyle-related or environmental causes of pituitary tumors, it is important to remember that there is nothing people with tumors could have done to prevent them.

Last Medical Review: 01/11/2013
Last Revised: 01/11/2013