Treatment of Functional (Hormone-Making) Pituitary Tumors

The treatment of functional pituitary tumors depends on which type of hormone they make.

Treatment of lactotroph adenomas or prolactin-secreting adenomas (prolactinomas)

Unlike most other pituitary tumors, surgery is usually not the first treatment for these tumors. Sometimes these tumors can just be watched and nothing needs to be done right away. Blood prolactin levels are checked regularly. If they start to go up, an MRI can be done to look for an increase in tumor size. Treatment can then be started as needed.

Medicines that block the production of prolactin (like cabergoline or bromocriptine) are used first. (See Medicines to Treat Pituitary Tumors.) They usually work so well that surgery isn't needed.

These drugs also shrink most prolactin-secreting macroadenomas. Even when the tumors don’t shrink, these drugs often keep them from getting bigger.

Within 3 months of starting drug treatment, the blood prolactin level is measured again and an MRI scan of the pituitary is done to see if the medicine is working. If so, treatment may be continued for the rest of the patient’s life. For some people, if treatment with these medicines has worked and over time, MRI scans show no tumor, the treatment may be stopped. These people will need to have regular MRIs to see if the tumor comes back. On the other hand, if after 6 months the tumor hasn’t responded well enough, or if serious side effects occur, then surgery is considered.

Some doctors recommend surgery in special cases, such as for people who cannot tolerate the drugs, or for women who want to become pregnant. (The drugs must be stopped during pregnancy, and pregnancy might cause the tumor to grow quickly.) Surgery can also be used when drug treatment doesn't work.

Radiation may be used if drug treatment and surgery do not work.

Treatment of somatotroph or growth hormone-secreting adenomas

Adults with these tumors often have acromegaly, while children have gigantism.

Surgery is usually the first treatment for these adenomas, but it often can’t remove all of the tumor. Sometimes, a somatostatin analog (see below) is given for a few months before surgery. This may cause the tumor to shrink, which could improve the chance that the surgery will remove all of the tumor, but doctors can’t be certain before trying that this will help.

If growth hormone and insulin-like growth factor-1 (IGF-1) levels remain high after surgery, many experts recommend treating with medicine first. Radiation therapy is another option, but it's used most often when surgery and drug treatments don’t work. (This is because radiation is very slow to act and over time it can lead to lowered levels of other pituitary hormones.)

Octreotide (Sandostatin), lanreotide (Somatuline Depot), and pasireotide (Signifor LAR) are man-made forms of the natural hormone somatostatin (they're called somatostatin analogs). These drugs return IGF-1 to normal levels in about 2 out of 3 patients. They are taken as injections, usually about once a month. The dose of these drugs may need to be adjusted based on blood IGF-1 levels.

Because these drugs work well and can be given monthly, doctors have started to question whether surgery should always be the first treatment for people with somatotroph adenomas. In those who might have problems with surgery, such as people with other major health problems, these drugs might be a good choice as the first treatment.

Another drug, pegvisomant, works by blocking the action of growth hormone. It can be used if somatostatin analogs (octreotide, lanreotide, or pasireotide) aren’t doing enough to block growth hormone production.

Drugs such as cabergoline or bromocriptine can be used along with a somatostatin analog. This helps reduce growth hormone levels in about 1 out of 2 patients. But some patients have trouble tolerating the high doses often needed for these drugs to work. The good thing about these drugs is that they're taken as pills.

If surgery and drug treatments don’t work, radiation therapy may be used.

Treatment of corticotroph or corticotropin (ACTH)-secreting adenomas

These tumors cause the adrenal glands to make too much of the steroid hormone cortisol, which leads to Cushing’s disease. (See Signs and Symptoms of Pituitary Tumors.)

Surgery is usually the main treatment. If the surgery doesn’t remove the tumor completely or if it grows back, the main options are a second surgery or radiation therapy. Radiation can often take months or years to work, so medicines may be given to help control cortisol levels in the meantime.

If surgery and radiation don’t control cortisol levels, treatment options may include using medicines or removing both of the adrenal glands (see below).

Several different types of medicines can be used to help control cortisol levels or limit the effects of this hormone in the body. (See Medicines to Treat Pituitary Tumors.) But medicines don't work as well for ACTH-secreting tumors as they do in some other types of pituitary tumors. And some of these drugs can have serious side effects that make them hard to take for a long time.

If medicines aren’t helpful, or if the patient can’t take them because of side effects, both adrenal glands can be removed with an operation called a bilateral adrenalectomy. This can usually be done with laparoscopic surgery, using small incisions in the belly instead of one large one. The surgeon works through these small incisions with special long, thin instruments, including one with a tiny video camera lens on the end (called a laparoscope) for looking into the belly. Adrenalectomy stops all cortisol production, so high cortisol levels will no longer be a problem. But after surgery patients will need to take pills to replace the adrenal steroid hormones for the rest of their life.

If the adrenal glands are to be removed, the pituitary gland will first be treated with radiation. If this isn’t done, removing the adrenals can cause the pituitary tumor to get larger and even start growing into the structures near the pituitary. This is known as Nelson syndrome. When the adenoma gets large, it can damage the normal parts of the pituitary gland, causing problems from hormone deficiency. It can also lead to high levels of ACTH. Because ACTH is a lot like the hormone that causes tanning of the skin, the high ACTH levels make the skin darker.

Treatment of thyrotroph or thyrotropin (TSH)-secreting adenomas

The treatment of choice for these tumors is surgery, which usually works well. Sometimes medicines are used before surgery to correct thyroid hormone levels and help shrink the tumor.

Sometimes radiation therapy may be used along with surgery. But radiation is not always helpful, and medicines may be needed to control the tumor’s hormone production if surgery didn't work. Some of the drugs that can be helpful include octreotide, lanreotide, cabergoline, and bromocriptine. These are usually used only if other treatments have failed to control the tumor.

It’s important to treat the pituitary tumor to keep it from damaging nearby structures. Drugs that stop the thyroid gland from making thyroid hormone can actually make things worse because reducing thyroid hormone production may cause the TSH-secreting pituitary tumor to grow.

Treatment of gonadotroph or gonadotropin (FSH/LH)-secreting adenomas

The hormones made by these tumors rarely cause major symptoms, so these tumors are often not found until they are large (macroadenomas) and pressing on nearby structures.

Treatment of these tumors is similar to that used for non-functional adenomas. Surgery is often the best option because it works right away. Radiation may be given after surgery.

Follow up with frequent MRI scans will show if the tumor is growing back. If it is, options include radiation (if it hasn’t been given already) or medicines such as dopamine agonists (cabergoline or bromocriptine) or somatostatin analogs (octreotide or lanreotide).

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

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Last Revised: November 2, 2017

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