Hormones are chemical messengers that regulate specific body functions. They are produced by various glands in the body and enter the bloodstream, where they travel to other tissues and exert their influence. Certain hormones can influence the growth of cancerous tumors. Hormonal therapy is used in cancer treatment to augment or interfere with the activity of these hormones.

Hormones are responsible for many functions in our bodies. For example, the thyroid gland secretes thyroid hormone, which has a role in the regulation of body temperature, reproduction, bone health, and glucose metabolism—just to name a few. The parathyroid gland secretes parathyroid hormone, which is the single most important hormone controlling the calcium balance of the blood. The gonads (testes in men and ovaries in women) produce the steroidal sex hormones: estrogen, progesterone, and testosterone, which are responsible for the secondary sex characteristics. These examples, which represent only a handful of the hormones circulating in our bodies, illustrate how essential hormones are to health.

  • How does hormonal therapy work?
  • What is hormonal therapy used for?
  • What are the types of hormonal therapy?
  • What adverse effects can occur with hormonal therapy?
  • Which cancers is hormonal therapy used to treat?

How Does Hormonal Therapy Work?

Some tumors arise in tissues that are sensitive to hormonal growth control. Tissues that are greatly affected by hormones include the breast and prostate. Estrogen promotes growth of some breast cancers, while testosterone promotes growth of some prostate cancers.




What Is Hormonal Therapy Used For?


What Are the Types of Hormonal Therapy?

Drug Therapy

Drugs used in hormone therapy fall into the following broad classifications:

  • Estrogens and anti-estrogens
  • Androgens and anti-androgens
  • Progestins
  • Gonadotropin-releasing hormone (GnRH) analogues
  • Aromatase inhibitors
Estrogens and Anti-estrogens

One of estrogen's normal physiologic functions is to promote the development of female secondary sex characteristics. In adults, estrogen continues to stimulate the growth of cells in the glandular ducts of the breasts and the endometrial lining of the uterus. Common estrogens and anti-estrogens used for hormonal therapy are selective estrogen receptor modulators and diethylstilbestrol (DES).

Selective Estrogen Receptor Modulators


Examples of SERMs include the following:

  • Toremifene—This is used in the treatment of metastatic breast cancer.
  • Raloxifene—This is currently used to treat osteoporosis. It is also used to help reduce the risk of breast cancer in postmenopausal women with osteoporosis..

DES is a synthetic estrogen. It used to be the primary hormonal therapy for postmenopausal metastatic breast cancer. However, it has largely been replaced by tamoxifen, which has similar efficacy, but lower toxicity. DES is associated with a risk of developing life-threatening blood clots. DES is sometimes used in metastatic breast cancer that is hormonally sensitive, but has not responded to multiple other hormonal therapies. DES is also used in men with metastatic prostate cancer.


Androgens and Anti-androgens



Examples of androgens include:

  • Fluoxymesterone
  • Methyltestosterone

Anti-androgens are used in men with metastatic prostate cancer. They are androgen receptor antagonists, meaning that anti-androgens bind to the androgen receptor and prevent dihydrotestosterone from binding. Dihydrotestosterone stimulates new growth of prostate cells, including cancerous prostate cells. These medications are generally used with orchiectomy or GnRH analogues.

Examples of anti-androgens include:

  • Flutamide
  • Bicalutamide
  • Nilutamide



Progestins are commonly used in the management of advanced uterine cancer. They can also be used for advanced breast cancer, although this use has been less common because of the numerous antiestrogen treatment options available. Occasionally, progestins are used as hormonal therapy for prostate cancer.

Examples of progestins include:

  • Megestrol
  • Progesterone acetate
Gonadotropin-releasing Hormone (GnRH) Analogues



Examples of GnRHs include:

  • Goserelin
  • Leuprolide
Aromatase Inhibitors



Examples of aromatase inhibitors include:

  • Aminoglutethimide
  • Letrozole
  • Anastrozole


Thyroid Replacement Therapy (Synthroid or Levothyroxine)


  • To suppress any thyroid cancer cells from growing back



The testes are the main source of testosterone production. For prostate cancer, orchiectomy, removal of the testes, may be considered in advanced cases.

What Adverse Effects Can Occur With Hormonal Therapy?

Hormonal therapies do have side effects, some of which are severe, but they are usually not life-threatening. Side effects usually occur when the hormonal agents affect tissues in the body other than the target tissues. The goal for future development of hormonal agents will be to design a therapy that will attack only the target tissues, while sparing those associated with side effects.


Estrogens and Anti-estrogens


Hot flashes are the most common side effect of SERMs (anti-estrogens). In addition, women may experience vaginal bleeding and discharge, mood swings, and visual disturbances. Uterine cancer, blood clots, and cataracts are rare, but serious side effects.

Tamoxifen has been associated with a 3-fold increase in endometrial cancer incidence when compared to the general population. However, the absolute risk is very small..

Androgens and Anti-androgens

Androgen's side effects are masculinizing effects, including hirsutism, male-pattern baldness, voice lowering, acne, and enhanced sex drive.

The most common side effect of anti-androgens is gastrointestinal distress— diarrhea, sometimes with abdominal pain and cramping. Gynecomastia frequently occurs in men, but can be controlled with concomitant therapy. A rare, but possibly fatal, complication is liver toxicity. Nilutamide has 2 unique side effects: night blindness and lung toxicity.



Gonadotropin-releasing Hormone (GnRH) Analogues


Aromatase Inhibitors

Aromatase inhibitors can cause osteoporosis and bone fractures. Other side effects include lack of energy, high blood pressure, nausea, vomiting, hypothyroidism, and skin rash.



Which Cancers Is Hormonal Therapy Used to Treat?


Breast cancerThyroid cancerUterine (endometrial) cancer

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