Hormones are vital for the body to function properly and can directly influence fertility.

The gonads, the primary reproductive organs, are the testes in the male and the ovaries in the female. These organs are responsible for producing the sperm and ova, but they also secrete hormones and are considered to be endocrine glands.

Hormonal treatments for cancer can either temporarily or permanently alter the production of hormones and can affect fertility in two ways:

• The production of sperm or eggs is affected
• Sexual desire and/or ability are affected.

Effects of hormonal treatment on the reproductive system in men

Testes

Male sex hormones, as a group, are called androgens. The principal androgen is testosterone, which is secreted by the testes. Small amounts of androgen are also produced by the adrenal cortex.40  Production of testosterone begins during foetal development, continues for a short time after birth, nearly ceases during childhood, and then resumes at puberty. This steroid hormone is responsible for:

• The growth and development of the male reproductive structures
• Increased skeletal and muscular growth
• Enlargement of the larynx accompanied by voice changes
• Growth and distribution of body hair
• Libido

Hormonal treatments are not usually used for cancer of the testes but testicular function can be affected by hormonal treatments used for other cancers such as prostate cancer.

Prostate

Hormonal treatment for cancer of the prostate reduces circulating testosterone. Hormonal treatments include surgery to remove the testes or individual hormonal drugs that reduce the amount of testosterone in the body. Some of which are listed here:

• Bicalutamide (Casodex®)
• Buserelin (Suprefact®)
• Cyproterone acetate (Cyprostat®)
• Flutamide (Drogenil®)
• Goserelin (Zoladex®)
• Leuprorelin acetate (Prostap® SR, Prostap® 3)
• Diethylstilbestrol (Stilboestrol®)
• Triptorelin (Decapeptyl® SR, Gonapeptyl Depot®)

Men with low levels of testosterone may experience decreased semen production. If oestrogen therapy is used this can cause erectile dysfunction, penile and testicular atrophy and altered spermatogenesis.(41)

Effects of hormonal treatment on the female reproductive system  

Ovaries

Two groups of sex hormones are produced in the ovaries: oestrogen and progesterone. These are steroid hormones that contribute to the development and function of the female reproductive organs and sex characteristics. At the onset of puberty, oestrogen promotes:

• Breast development
• Distribution of fat in the hips, legs, and breasts
• Maturation of reproductive organs such as the uterus and vagina

Progesterone causes the lining of the uterus to thicken in preparation for pregnancy. Together, progesterone and oestrogen are responsible for the changes that occur in the uterus during the menstrual cycle.

Hormone treatments are often used to treat breast cancer and sometimes uterine cancer. Treatments include anti oestrogen drugs, progesterone and aromatase inhibitors some of which are listed here:

• Anastrozole (Arimidex®)
• Exemestane (Aromasin®)
• Goserelin (Zoladex®)
• Letrozole (Femara®)
• Medroxyprogesterone acetate (Provera® Depo-Provera® Farlutal®)
• Megestrol acetate (Megace®)
• Tamoxifen
• Toremifene (Fareston®)

Although a women’s fertility is not directly affected by a loss of sexual desire there may be an indirect effect due to hormonal treatments causing a reduced libido.

The ovaries can be affected by hormonal treatments such as those used in breast cancer. Endocrine therapy can slow or stop the growth of breast cancer cells either by altering the levels of particular hormones which are naturally produced in the body, or preventing the hormones from being taken up by the cancer cells.(42)  As a result fertility may be affected, although it may return when the hormonal treatment has stopped (if the woman is still premenopausal).

Although hormonal treatments can affect fertility (sometimes only temporarily) it is important that contraception is used as pregnancy can still occur during this time and the effects upon the foetus are unknown.