Hi Carol,
I too am 50 and was pre-menopausal when diagnosed 4 years ago. I had one period after chemo, started tamoxifen in 2013 and haven't had a period since so am well and truly menopausal now. My oncologist did suggest switching from tamoxifen to an aromatase inhibitor (AI) after it became clear I was menopausal as I understand they are slightly more effective in preventing BC recurrence in menopausal women.
However, I've opted to remain on tamoxifen (and my oncologist is fine with that) as I have not had any significant side effects from it and everything I have read about the day to day effects of AIs has been very negative - significant bone/joint pain, vaginal atrophy and dryness, complete loss of libido, etc These symptoms are a result of blocking all estrogen production in the body and sound bloody awful to me.
Tamoxifen works differently. Your body still makes estrogen (though not as much as before menopause) but the tamoxifen blocks it from feeding any stray cancer cells that might still be in the body. You get to keep a little bit of estrogen and the benefits that go with that - better bones, skin, sexual health etc - but you are still pretty well protected from cancer.
I know most women with estrogen positive BC are put on AIs but personally - for me - I think tamoxifen is a much better option.
Sure it's not perfect. Some people get unpleasant side-effects from it too and there are slightly increased risks of endometrial and uterine cancer down the track. There is also an increased risk of blood clot/strokes.
I try to counter these things by working hard to stay fit and healthy. I run and do weights regularly and I am careful about what I eat. I am certainly not perfect but I have managed to maintain a healthy weight so far and generally I feel really good.
Just wanted to mention the tamoxifen option as I feel it is not really raised as an option for menopausal women even though it works almost as well as AIs and it doesn't seem to have as many nasty side effects (although everyone is different of course). Good luck with your treatment, whatever you decide.