Drug therapy for pituitary gland tumours

Drug therapy is usually used to treat pituitary gland tumours that make too many hormones (functioning tumours). The drugs work by changing hormone levels so they return to normal.

Drug therapy is given for different reasons. You may have drug therapy to:

• control hormone levels in the body
• manage symptoms caused by abnormal hormone levels
• shrink a tumour before other treatments such as surgery or radiation therapy (called neoadjuvant therapy)
• destroy cancer cells left behind after surgery and reduce the risk that the cancer will come back (called adjuvant therapy)
• destroy cancer cells in the body
• ease the symptoms of advanced pituitary gland cancer (called palliative therapy)

Your healthcare team will consider your personal needs to plan the drugs, doses and schedules of targeted therapy. You may also receive other treatments.

Which drugs are used for pituitary gland tumours depend mainly on the type of tumour and hormone levels in the body.

Dopamine is a chemical in the brain (called a neurotransmitter) that sends signals or messages from one neuron to another neuron. It normally slows or stops the pituitary gland from making prolactin until it is needed. Dopamine agonists are drugs that act like dopamine to lower the amount of prolactin being made.

Dopamine agonists are the main treatment, and often only treatment, for prolactin-producing tumours. They may also be used to treat thyroid-stimulating hormone (TSH)–producing tumours and gonadotropin-producing tumours.

The most common dopamine agonists used are bromocriptine (Parlodel) and cabergoline (Dostinex). These drugs are given as a pill. How often they are taken depends on the type and dose of the drug.

Somatostatin analogues are drugs that lower the amount of hormones made and released by certain functioning pituitary gland tumours. They are mainly used after surgery to treat tumours that make too much growth hormone and lead to increased growth of the skull and the bones of the face, jaw, hands and feet (a condition called acromegaly). They may also be used to treat tumours that make too much thyroid-stimulating hormone (TSH) or too much adrenocorticotropic hormone (ACTH).

Somatostatin analogues are given as injections into the muscle or under the skin. They include:

• octreotide (Sandostatin)
• lanreotide (Somatuline Autogel)
• pasireotide (Signifor)

Octreotide is the most common somatostatin analogue used. A fast-acting form of octreotide (octreotide IR) is given several times a day. This form of octreotide is most often used for a short time when the drug is first started to check that you can cope with it. A long-acting form of octreotide (octreotide LAR) that is given once a month is also available.

Lanreotide may be used instead of octreotide LAR because it works in the same way. It is given once a month.

Pasireotide is used to treat adults with Cushing disease caused by an ACTH-producing tumour when surgery can’t be done or if surgery didn’t work. It is given twice a day.

Growth hormone receptor antagonists are drugs that block growth hormone from working properly. They are used to control acromegaly caused by growth hormone–producing tumours.

Pegvisomant (Somavert) is the growth hormone receptor antagonist used. It is given by injection once a month. It is usually used after somatostatin analogues are tried and don’t work.

Steroidogenesis inhibitors block cortisol and other steroid hormones from being made by the adrenal glands. They are used to treat Cushing disease caused by an ACTH-producing tumour. They are usually used if surgery has not controlled cortisol levels in the body.

Many steroidogenesis inhibitors are given as a pill and include:

• ketoconazole
• metyrapone
• mitotane (Lysodren)
• aminoglutethimide (Cytadren)

Hormone replacement is usually needed when the pituitary gland is not making enough of any of its hormones (called hypopituitarism). This can happen if part or all of the pituitary gland has been removed during surgery or a tumour has damaged the pituitary gland.

Hormone replacement may include giving:

• hydrocortisone to replace cortisol that ACTH normally tells the adrenal glands to make
• levothyroxine (Synthroid, Eltroxin) to replace thyroxine, which is the thyroid hormone controlled by TSH
• synthetic growth hormone made in a lab to replace the natural growth hormone
• estrogen and progesterone to replace female sex hormones
• testosterone to replace the male sex hormone
• desmopressin to replace antidiuretic hormone (ADH)

How hormone replacement is given and how often it is given depend on the type of hormone being replaced. Hormone replacement drugs are available in several different forms, including pills, injections, gels and nose sprays.

Chemotherapy uses anticancer (cytotoxic) drugs to destroy cancer cells. It may be used to treat pituitary carcinoma. There is no standard chemotherapy treatment for pituitary carcinoma. But some studies have shown benefit in using temozolomide (Temodal).

Side effects can happen with any type of treatment for pituitary gland tumours, but everyone’s experience is different. Some people have many side effects. Other people have few or none at all.

If you develop side effects, they can happen any time during, immediately after or a few days or weeks after drug therapy. Sometimes late side effects develop months or years after drug therapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.

Side effects of drug therapy will depend mainly on the type of drug, the dose, how it’s given and your overall health.

Dopamine agonists may cause:

• dizziness
• nausea and vomiting
• low blood pressure
• headaches

Somatostatin analogues may cause:

• gallbladder problems, including gallstones
• diarrhea
• fatty stool (steatorrhea)
• pain in the abdomen
• nausea and vomiting
• high or low blood sugar (glucose) levels

Pegvisomant (Somavert), a growth hormone receptor antagonist, may cause:

• pain or a reaction at the injection site
• diarrhea
• nausea
• flu-like symptoms

Steroidogenesis inhibitors may cause:

• loss of appetite
• nausea and vomiting
• diarrhea
• changes to memory

Tell your healthcare team if you have these side effects or others you think might be from drug therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Details on specific drugs change regularly. Find out more about sources of drug information and where to get details on specific drugs.