Hormonal therapy for cancer of unknown primary

A few people with cancer of unknown primary (CUP) may have hormonal therapy. It is a treatment that adds, blocks or removes hormones. Hormones are substances that control some body functions, including the activity and growth of cells. Changing the levels of or blocking certain hormones can slow the growth and spread of cancer cells. Drugs, surgery or radiation therapy can be used to change hormone levels or block their effects.

You may be offered hormonal therapy if your doctors think your type of CUP will respond to it. Hormonal therapy may be used to:

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

Your healthcare team will consider your personal needs to plan your hormonal therapy. You may also receive other treatments.

Hormonal therapy by type of CUP

You may be offered hormonal therapy if your doctors think the CUP started in the breast or prostate.

Hormonal therapy for CUP that may have started in the breast

Hormonal therapy may be offered to women who have CUP in lymph nodes under the arm and doctors think that the breast is the primary site. The hormonal therapy drugs used are the same as those given for breast cancer and may include:

  • tamoxifen (Nolvadex, Tamofen)
  • anastrozole (Arimidex)
  • letrozole (Femara)
  • exemestane (Aromasin)
  • goserelin (Zoladex)

Find out more about hormonal therapy for breast cancer.

Hormonal therapy for CUP that may have started in the prostate

The prostate may be the primary site in men who have CUP in a bone or a high prostate-specific antigen (PSA) level. The hormonal therapy drugs used are the same as those given for prostate cancer and may include:

  • leuprolide (Lupron, Lupron Depot, Eligard)
  • goserelin (Zoladex)
  • flutamide (Euflex)
  • bicalutamide (Casodex)

Find out more about hormonal therapy for prostate cancer.

Side effects

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

Side effects of hormonal therapy will depend mainly on the type of drug, the dose and your overall health. Some common side effects of hormonal therapy drugs used for CUP are:

Tell your healthcare team if you have these side effects or others you think might be from hormonal therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them. They can also provide more information about sexuality and cancer.

Information about specific cancer drugs

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

Questions to ask about hormonal therapy

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

Expert review and references

  • Cancer Care Ontario. Drug Formulary. Toronto, ON: Cancer Care Ontario;
  • Fizazi K, Greco FA, Pavlidis N, et al . Cancers of unknown primary site: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. Oxford University Press; 2011.
  • Greco FA & Hainsworth JD . Cancer of unknown primary site. DeVita VT Jr, Lawrence TS, & Rosenberg SA. Cancer: Principles & Practice of Oncology. 10th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2015: 113:1720-1737.
  • Hainsworth JD, Greco FA . Chemotherapy of carcinoma of unknown primary site. Perry MC, Doll DC, Freter CE. Perry's The Chemotherapy Source Book. 5th ed. Lippincott Williams Wilkins; 2012: Chapter 37. http://www.lwwoncology.com.
  • Kim KW, Krajewski, KM, Jagannathan JP, et al . Cancer of unknown primary sites: what radiologists need to know and what oncologists want to know. AJR: American Journal of Roentgenology. The American Roentgen Ray Society; 2013.
  • National Comprehensive Cancer Network. Occult Primary (Cancer of Unknown Primary [CUP]) (Version 3.2014). http://www.nccn.org/professionals/physician_gls/pdf/occult.pdf.