Causes and Risk Factors for Pituitary Tumors
Pituitary tumors are often called pituitary adenomas cause symptoms when they are functional. Because of the excessive hormones produced by functional tumors they can cause symptoms whereas non-functional tumors often become large (macroadenomas) before they are noticed. This is because these tumors do not cause symptoms until they press on nearby nerves, parts of the brain, or other parts of the pituitary.
Non-functional adenomas that cause no symptoms are sometimes found when an MRI or CT scan done for other reasons. They are often just watched closely without needing treatment as long as they are not causing problems.
Most of the time, a functional adenoma makes too much of a single pituitary hormone and the symptoms from these adenomas are based on which hormone they make. Therefore these tumors can be found while they are still fairly small (microadenomas).
The exact cause of most pituitary tumors is unknown. Certain changes in DNA of a person can cause cells in the pituitary to produce a tumor. DNA is the chemical in each of our cells that makes up our genes and gives instructions how our cells function. DNA of a person may have many affects more than appearance. Genes are the factor that control the growth of new cells, divide into new cells, and death.
Genes that help cells grow, divide, and stay alive are called oncogenes where as genes that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. DNA changes that turn on oncogenes or turn off tumor suppressor genes can cause tumors.
Some people inherit changes of gene or mutations from their parents that greatly increase their risk for developing pituitary tumors. However gene mutations occur during life rather than having been inherited. These acquired mutations can be caused by outside exposures, such as radiation or cancer-causing chemicals. Most pituitary tumors are not cancers, and there are no known environmental causes for these tumors. When a cell divides, without having an outside cause, there might be a possibility of gene changes in these tumors.
Non-hereditary pituitary tumors that does not run in families can acquired mutations in AIP gene. GNAS1 is responsible for most of the growth hormone-secreting adenomas. When there is a loss of the regulatory mechanism that normally keeps the pituitary cells from growing and making too much hormone, these tumors can occur. There is no known way to prevent pituitary tumors as these have not been linked with any known outside risk factors.
The probability of getting a disease from any factor is known as risk factor. But having a risk factor, or even many risk factors, does not mean that you will necessarily get the disease. Many people who get the disease may have few or no known risk factors. There are no known environmental or lifestyle-related risk factors for pituitary tumors. Mostly these are related to genetics.
Most people who develop pituitary tumors do not have a family history of the disease. But rarely, pituitary tumors can run in families the reason of which is unknown. These are due to certain changes in the genes of a person that are inherited from a parent. When pituitary tumors run in families, they are found along with other types of tumors as part of an inherited genetic syndrome.
Pituitary tumors can be a part of a syndrome that includes an increased risk of other types of tumors. These syndromes are caused by abnormal changes or mutations) in the genes of a person. These include:
This is a hereditary condition in which people have a very high risk of developing tumors of the pituitary, parathyroid, and pancreas. It can occur due to changes in the gene MEN1. This can be passed on to about half of the children of an affected parent. You should discuss testing for this condition with your doctor if the MEN1 syndrome affects your family.
This syndrome includes increased risks of pituitary tumors and certain other tumors which is very rare. Inherited changes in CDKN1B gene can cause MEN4.
This syndrome occurs due to changes in GNAS1 gene. These are not inherited but occur before birth. People with this syndrome have brown patches on their skin and develop many bone problems. They can also have pituitary tumors along with hormone problems.
Most of the cases are caused by inherited changes of PRKAR1A gene. In this syndrome people can have heart, skin, and adrenal problems which is very rare. They also have a high risk of a number of different types of tumors, including pituitary tumors.