Prolactinomas are very common, accounting for 30 percent of all pituitary tumors. The tumors produce the hormone prolactin, which among other actions stimulates the breast to produce milk and helps to regulate mood.
Large prolactinomas may cause problems with vision as the tumor presses on the nearby optic nerve.
In men, a prolactinoma may lead to erectile dysfunction. Symptoms may include impotence, or the inability to achieve an erection. In women, the hormone prolactin stimulates the breasts to make milk (lactation) during and after pregnancy. Symptoms may include lactating breasts not associated with pregnancy or the lack of expected menstrual periods.
If your doctor suspects that you have a prolactinoma, a blood test may be performed to measure your levels of prolactin. An MRI scan may also be used to determine the exact size and location of the tumor.
More than 90 percent of people who develop a prolactinoma can be treated with medication alone. At Memorial Sloan-Kettering, we usually prescribe cabergoline (Dostinex®). The drug comes in pill form and is generally taken once a week.
Surgery is not commonly used to treat prolactinomas, but it is recommended in patients who develop significant side effects or who do not respond to the medication. Cabergoline is not approved for use during pregnancy, so women planning to conceive may also be candidates for surgery.
If surgery is necessary, Memorial Sloan-Kettering surgeons may use a minimally invasive approach called transnasal transsphenoidal resection to remove pituitary tumors. Surgeons are able to bypass brain tissue, operating instead through an incision inside the nasal passage. The risk for neurologic complications with this approach is very low, and the surgery leaves no visible scar.
Your doctor may also recommend radiation therapy, such as stereotactic radiosurgery in which special equipment is used to give a single large dose of radiation to a tumor. We may also recommend intensity-modulated radiation therapy, which uses radiation beams of varying intensity to precisely match tumor angles and shapes, and thereby reduce the risk of damage to optic nerves and other delicate structures in this area.