Hi @Shann. If you are still menstruating Tamoxifen is the only one for you. If you are not, you can take either that or an aromatase inhibitor.
Did your periods stop because of your cancer treatment? If they did and they haven't come back, your GP or oncologist can order a blood test to see if your ovaries are trying to pump out oestrogen again. FSH, LH and OST are the acronyms used I believe.
If your oestrogen levels are on the rise your doctor will want to either put you on Tamoxifen, or suppress your oestrogen production with a monthly injection of zoladex and give you an AI (Letrozole, Anastrozole, Exemestane).
All this depends on your age as well. At 51 when I was diagnosed I was still getting periods, but it's the average age for menopause and Letrozole is, by a small percentage, the best hormone treatment. As i am on the cusp, for the first two to three years I have to have this blood test every three months to make sure my ovaries aren't trying to rev up again. My oncologist said she's had 55yo patients suddenly getting a period again!
Hope that's clear! K xox