Doctors commonly treat prolactinomas with medicines. More rarely, surgery or radiation therapy may be used. The goals of treatment are to
- bring prolactin levels back to normal
- shrink the tumor
- make sure the pituitary gland is working properly
- correct any problems caused by the tumor, such as menstrual problems, milky discharge from the breasts, low testosterone levels, headaches, or vision problems
Medicines
Medicines called dopamine agonists control prolactin levels and shrink the tumor very effectively. These drugs mimic the effects of the brain chemical dopamine.
Two dopamine agonists are most commonly used to treat prolactinomas
- bromocriptine, a drug that must be taken twice or three times daily
- cabergoline, a drug that can be taken once or twice per week
Cabergoline is the preferred drug for treating prolactinomas, because it is more effective than bromocriptine and has fewer side effects.
Outcomes. For most small prolactinomas, dopamine agonists bring prolactin levels back to normal and shrink tumors in 4 out of 5 patients.
Side effects. Common side effects of the drugs include nausea, vomiting, and dizziness. Both medicines should always be taken with food. Starting treatment at a low dose and taking the medicine at bedtime can reduce side effects.
Complications. Although dopamine agonists have been linked to heart valve damage, these problems were found mainly among people taking these medicines to treat Parkinson’s disease. These patients typically take much higher doses (usually about 10 times higher) of these medicines than are used to treat prolactinomas. If you need to take a high dose of a dopamine agonist, your doctor may order an echocardiogram (echo) to check your heart valves and heart function. Rarely, psychiatric disorders related to impulse control, such as compulsive gambling, have been seen in people taking these medicines.
Duration of treatment. You may have to take these medicines for a long time to prevent the tumor from growing back, especially if the prolactinoma is large. After 2 years, the medicines may be slowly reduced and stopped if prolactin levels are normal and the tumor is no longer visible. But if your prolactin level goes back up again, you may need to go back on the medicine for as long as needed to bring your prolactin level under control.
Surgery
Although doctors most often treat prolactinomas with medicines, in some cases surgery may be an option. Examples include
- you can’t tolerate the medicines
- the medicines aren’t working for you
- you take antipsychotic medicines that interact with the medicines used to treat prolactinomas
In some cases, when a prolactinoma is large, a woman may choose to have surgery to remove the tumor before trying to become pregnant.
Two types of surgery may be used
- Transsphenoidal surgery is most commonly used to treat prolactinoma. The surgery is done through an incision, or cut, at the back of the nasal cavity or under the upper lip.
- Transcranial surgery is used more rarely if the tumor is large or has spread to other areas. The surgeon removes the tumor through an opening in the skull.
Outcomes. The success of the surgery depends on many factors, including
- skill and experience of the surgeon
- size and location of the tumor
When done by an experienced surgeon, the surgery corrects prolactin levels in about 90 percent of people with small tumors and 50 percent of those with large tumors. For people with larger prolactinomas that can only be partly removed, medicines often can return prolactin levels to a normal range after surgery.
Side effects and complications. Side effects of the surgery can include
- low pituitary function, or hypopituitarism
- temporary diabetes insipidus, a condition that leads to frequent urination and excessive thirst
- cerebrospinal fluid leak
- local infection
Radiation
More rarely, if medicines and surgery fail to reduce prolactin levels, radiation therapy may be used. This type of treatment uses high-energy x-rays or particle waves to kill tumor cells. Depending on the size and location of the tumor, the total radiation dose is delivered in one session, or in lower doses over the course of 4 to 6 weeks.
Outcomes. Prolactin levels return to normal in 1 out of 3 patients treated with radiation therapy. However, as radiation treatment lowers prolactin levels over time, it may take years to reach this outcome. Your doctor is likely to prescribe medicines while you wait to see results.
Side effects and complications. The most common side effect is low levels of thyroid hormone. In up to half of patients, radiation therapy may also lead to a decrease in other pituitary hormones. Vision loss and brain injury are rare complications. Rarely, other types of tumors can develop many years later in areas that were in the path of the radiation beam.