Endocrine treatment is advised by your consultant if they find that your breast cancer is oestrogen receptor (ER) positive. As in some breast cancers it is found that the oestrogen hormone in the body aids in the growth of the cancer, all breast cancers are tested using tissues from a biopsy or from after your surgery. If the test suggests an ER positive breast cancer that would mean the oestrogen in your body is helping the cancer grow and you consultant will go over treatment options best suited for you.
Hormone therapy or endocrine treatment helps stops the effect of oestrogen on your breast cancer cells and each of the treatment drugs helps differently.
If you have not yet been through menopause then tamoxifen is recommened. Tamoxifen being an “oestrogen receptor blocker” works by stopping the cancer cells from taking up oestrogen. In some cases, a drug called goserelin or Zoladex can also be given to stop the ovaries from working as well.
If you have had menopause than a different tablet can be used. The commonest one used now is Letrozole (also known as Femara).
It works by preventing the body from making any oestrogen. This type of drug is known as an aromatase inhibitor or AI. They do not work in premenopausal ladies. Whatever kind of endocrine tablet you have you will normally have a single tablet a day for 5 years.
The commonest side effect of tamoxifen is weight gain whilst the aromatase inhibitors can make the joints and muscles ache. Having said that, most ladies have few, if any side effects and tolerate the tablets very well.
Anastrozole is used for hormone receptor-positive breast cancer. It has also been used to prevent breast cancer if you are at high risk. It is taken in a goserelin or Zoladex a tablet form.
Common side effects include body aches and pains, breast swelling, tenderness and pain, also constipation, diarrhea, nausea, vomiting and upset stomach.