Hormonal Therapy

Breast cancers are tested for oestrogen receptors (ER) and progesterone receptors (PR) on their surfaces as such cancers can be stimulated by oestrogen or progesterone to grow.

Hormonal therapy is aimed at blocking this effect. The drug recommended is dependent on the menopausal status of the women.

Hormonal therapy can cause some side effects, and they are dependent on the type of drug taken and can vary from one patient to another.

Tamoxifen

This drug blocks the action of oestrogen on the body but does not stop oestrogen from being produced. Tamoxifen may cause hot flashes, depression or mood swings, vaginal discharge or irritation, irregular menstrual periods and sometimes menopause.

Any unusual bleeding should be reported to the doctor. It is recommended for pre-menopausal women, but can be used in postmenopausal women.

Side Effects:

• Serious side effects from Tamoxifen are rare but Tamoxifen can cause the formation of blood clots in the veins, especially in the legs. In a very small number of women, Tamoxifen can cause cancer in the lining of the uterus. You may be referred to a gynaecologist to evaluate any unusual bleeding.

Aromatase lnhibitors (AI)

For post-menopausal women, another group of drugs called aromatase inhibitors (AIs) is also used in breast cancer hormonal treatment. Aromatase inhibitors work by blocking an enzyme called aromatase that the body uses to produce oestrogen.

The current Als such as anastrozole, letrozole and exemastane, are well-tolerated and are used in the treatment of early stage and advanced breast cancer.

Side Effects:

• Side effects of AI include hot flashes, mood changes, nausea, vaginal dryness, joint pain/stiffness, tiredness, lethargy and osteoporosis (including a higher risk of fractures compared to Tamoxifen).