Despite adequate local treatment of breast cancer (surgery +/- radiotherapy) a proportion of patients will develop spread to other organs in the body in the future. This indicates that these cells must have spread by the time that the cancer is removed from the breast.
The likelihood that breast cancer cells may have spread, and the prognosis of an individual patient, can be predicted by the pathology results and extra or adjuvant therapy may be used to try to control these tumour cells.
Adjuvant therapies include hormone therapy, chemotherapy and targeted treatments such as herceptin.
A number of hormone therapies are now available:
- TamoxifenTamoxifen has now been used for many years in breast cancer treatment. It is effective in all ages but is most effective in tumours that are rich in oestrogen receptors (ER). Oestrogen, one of the female hormones, stimulates the growth of breast cancer cells and tamoxifen blocks this effect. It is effective against tumour cells in any part of the body, not just the breast. As well as blocking the effect of oestrogen, it also has benefits similar to HRT (hormone replacement therapy) including reducing osteoporosis and decreasing the incidence of heart attacks.
Tamoxifen is taken as a single daily dose (20mg) at the same time each day. Side effects can include mild nausea or a slight metallic taste and these may improve if taken with food or at bedtime. Tamoxifen is usually recommended for a five year period if used on its own although more recently it has been used for shorter periods (2-3 years) prior to switching to one of the aromatase inhibitors (anastrazole, letrozole, exemestane).
Tamoxifen does have a number of possible side effects which are often most apparent in pre-menopausal patients. These may include mild indigestion, nausea, hot flushes and vaginal discharge or dryness. Periods may get lighter or stop altogether. Hair and nail growth may slow down. In very rare cases it can also cause cancer of the womb but this is very uncommon and very treatable.
Although Tamoxifen is a hormone treatment it is not a contraceptive, even if periods stop while on treatment.
- Anastrazole (Arimidex), Letrozole (Femara) and Exemestane (Aromasin) are known as Aromatase Inhibitors.
A new group of hormonal agents called aromatase inhibitors (AI’s) are now available for breast cancer treatment. They block the conversion of male to female hormones in post-menopausal women. They do not work however in pre-menopausal women. Current AI’s include anastrazole (Arimidex), letrozole (Femara) and exemestane (Aromasin).Recent research studies have shown that these drugs are at least as effective as Tamoxifen although Tamoxifen is much cheaper. In combination with tamoxifen their efficacy seems to be increased in certain clinical situations. Three years of Letrozole has been shown to significantly improve survival after five years of Tamoxifen in women with positive lymph nodes. 2-3 years of Exemestane has been shown to significantly increase survival after 2-3 years of Tamoxifen.In addition, the function of the ovaries can be blocked by medication (Zoladex) or surgical removal (oophorectomy). In the past radiotherapy was sometimes used to block the ovaries but the side effects have now made this particular treatment obsolete.
All these hormone treatments decrease the chance of tumour recurrence and improve survival following breast cancer surgery. They will also significantly reduce the risk of cancer in the other breast.