If your cancer was tested and found to be estrogen and/or progesterone receptor positive, that means its growth may have been dependent, at least in part, upon the naturally occurring estrogen and/or progesterone in your body.  In premenopausal women, the main source of these hormones is in the ovaries.  Post menopause, women produce trace quantities of androgens (a type of hormone) mostly in the adrenal glands.  Androgens are precursors of estrogens as they are converted to estrogens through the action of an enzyme in the body known as aromatase.

In premenopausal women, drugs are used (such as Tamoxifen) to block the estrogen receptors at the cellular level from absorbing estrogen so cancer is not able to grow.  In post-menopausal women, naturally occurring androgens that convert to estrogen, are stopped through the use of aromatase inhibitors.  These drugs block the aromatase enzymes and as a result prevent androgens from converting to estrogen.   If a cancer is estrogen receptor positive, these can help prevent the growth of cancer, depending on how high the receptor level is.

Side Effects

The most common side effects to these drugs are hot flashes, joint pain and stiffness, and bone loss.  Many women have no trouble with these therapies, however, some women do suffer from side effects and some to such an extent that they stop treatment.

Hot flashes: Often doctors will prescribe anti-depressant drugs like Lexapro or Effexor to help decrease the frequency of hot flashes.

Joint Pain and Stiffness:  Women whose vitamin D levels are below 45 are deemed to be vitamin D deficient and experience more pain than women who have vitamin D levels above 45.   Get your vitamin D level tested and then correct it by taking vitamin D supplements if you are deficient.   Not only can it reduce joint pain, it can also help prevent breast cancer recurrence. 

Bone loss is another concern. New studies have shown that taking bone density drugs can prevent bone loss and it can also help prevent cancer spreading to the bones.

Personal Note: I elected to have my ovaries removed and also have chosen NOT to do hormonal therapy.  My cancer was only slightly estrogen receptor positive (less than 10%) and progesterone negative, so, in my case, the drugs may not even be effective.  In addition, I started to see a naturopathic doctor who ran some tests and was able to provide a natural solution.

Oddly, no one ever tested me for my vitamin D level until I went to my naturopath – he wanted to see my vitamin D level up around 85-100 – it was 13!!  The vitamin D deficiency may have contributed to me getting cancer in the first place!!