Drug therapy for pituitary gland cancer

Almost all pituitary gland cancers are pituitary neuroendocrine tumours (PitNETs). Drug therapy is commonly used to treat a PitNET that makes too much of a certain hormone (called a functioning tumour). The drugs work by changing hormone levels back to normal. Drug therapy is a systemic therapy, which means that the drugs travel throughout the body.

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

• slow the growth of the tumour
• control hormone levels in the body
• manage symptoms caused by abnormal hormone levels
• relieve pain or control symptoms of a metastatic PitNET (called palliative therapy)

If you have drug therapy, your healthcare team will use what they know about the cancer and about your health to plan the drugs, doses and schedules.

The drugs used for PitNETs depend mainly on the type of tumour and hormone levels in the body.

Dopamine is a chemical in the brain. It works as a neurotransmitter, which means that it sends signals, or messages, from one neuron to another. Dopamine normally tells the pituitary gland to slow down or stop making prolactin.

Dopamine agonists are drugs that act like dopamine to lower the amount of prolactin being made.

Dopamine agonists are the main treatment for prolactin-producing tumours. They may also be used to treat thyroid-stimulating hormone (TSH)–producing tumours. Dopamine agonists can also be used for acromegaly or gigantism if surgery or radiation therapy is not effective.

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

Somatostatin is a hormone that tells the pituitary gland to stop releasing certain hormones.

Somatostatin analogues are drugs that work like somatostatin to lower the amount of certain hormones made by functioning PitNETs. They are mainly used after surgery to treat a tumour that makes too much growth hormone and cause acromegaly or gigantism. They may also be used to treat a tumour that makes 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. The ones used to treat PitNETs include:

• octreotide
• lanreotide
• pasireotide

Growth hormone promotes the growth of all tissues in the body, including bones and muscles. It allows bones and muscles to grow during childhood. In adults, it helps maintain body tissues.

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

Pegvisomant is the growth hormone receptor antagonist used for acromegaly. It’s given by injection. It’s usually used after somatostatin analogues 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 given if surgery doesn’t control the level of cortisol in the body.

The following steroidogenesis inhibitors are given as a pill to treat PitNETs:

• ketoconazole
• mitotane (Lysodren)

Hormone replacement therapy is usually needed when the pituitary gland is not making enough of 1 or more hormones (called hypopituitarism). This can happen if part or all of the pituitary gland has been removed with surgery or a tumour has damaged the pituitary gland.

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

Chemotherapy uses drugs to destroy cancer cells. These drugs target rapidly dividing cells throughout the whole body. This means that chemotherapy kills cancer cells but it can also damage healthy cells.

With most types of chemotherapy, the drugs travel through the blood to reach and destroy cancer cells all over the body, including cells that may have broken away from the primary tumour. This is described as systemic therapy.

You may have chemotherapy to treat metastatic PitNETs. If you have chemotherapy, your healthcare team will use what they know about the cancer and about your health to plan the drugs, doses and schedules.

The most common chemotherapy drug combination used to treat pituitary gland cancer is capecitabine and temozolomide. Sometimes, the targeted therapy drug everolimus is also used.

Chemotherapy drugs used for pituitary gland cancer are given as a pill.

Find out more about chemotherapy.

Side effects of drug therapy will depend mainly on the type of drug and your overall health. Tell your healthcare team if you have side effects that you think are from drug therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

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

The growth hormone receptor antagonist pegvisomant 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
• headaches
• liver disease

Chemotherapy drugs used for pituitary cancer may cause:

• diarrhea
• nausea and vomiting
• fatigue
• loss of appetite
• hand-foot syndrome
• sore mouth
• hair loss

Side effects of hormone replacement will depend on the type of hormone given. Find out more about the side effects of hormone therapy.