Hormone therapy for cancer of unknown primary

Hormones are substances that control some body functions, including how cells act and grow. Hormone therapy adds, blocks or removes hormones to slow or stop the growth of cancer cells that need hormones to grow. Hormone levels can be changed or blocked by drugs, surgery or radiation therapy.

A few people with cancer of unknown primary (CUP) may have hormone therapy. You may be offered hormone therapy if your doctors think the CUP will respond to it. If you have hormone therapy, your healthcare team will use what they know about the cancer and about your health to plan your treatment.

Hormone therapy may be the only treatment you have or it may be used along with other cancer treatments. Hormone therapy may be used to:

• treat the cancer
• relieve pain or control the symptoms of advanced CUP (called palliative therapy)

You may be offered hormone therapy if your healthcare team thinks the CUP started in the breast or prostate or if you have a neuroendocrine CUP.

Hormone therapy may be offered when the healthcare team thinks that the breast is the primary site of CUP in lymph nodes under the arm. The hormone therapy drugs used are the same as those given for breast cancer.

Find out more about hormone therapy for breast cancer.

The prostate may be the primary site of CUP that is found in a bone in people who have a high prostate-specific antigen (PSA) level. The hormone therapy drugs used are the same as those given for prostate cancer.

Find out more about hormone therapy for prostate cancer.

Well-differentiated neuroendocrine CUP may be treated with a type of hormone therapy drug called somatostatin analogues.

Somatostatin analogues lower the amount of hormones made and released by neuroendocrine tumours. They are used to slow down and control the growth of well-differentiated neuroendocrine CUP.

The somatostatin analogues used for neuroendocrine CUP are:

• octreotide (Sandostatin)
• lanreotide (Somatuline Autogel)

Find out more about drug therapy for neuroendocrine tumours, including somatostatin analogues.

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

Common side effects of hormone therapy drugs used for CUP that may have started in the breast or prostate are:

• hot flashes and sweating
• treatment-induced menopause
• weight gain
• fatigue
• tumour flare reaction

Common side effects for somatostatin analogues used for neuroendocrine CUP are:

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

Find out more about hormone therapy and side effects of hormone therapy. To make the decisions that are right for you, ask your healthcare team questions about hormone therapy.

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