Let me say, I'm not in the medical field, but there are alternatives to tamoxifen, the "armoatase inhibitors" - Femara and Arimidex, and Aromasin. The biggest thing is that you have to be post menapausal, and I would think at the age of 70 you are post menapausal. What I learned from my Oncologist, is the reason you have the hot flashes on Tamoxifen is because your not ovulating (i.e. post menapasal). My oncologist told me as soon as I stop ovulating, she is going to switch me off of Tamoxifen and onto probably Femara.
I've heard that the side effects of these drugs are a lot less than tamoxifen and work just as well if not better than tamoxifen, although hot flashes is still a side effect, they may be less.
Also, remember, you are the one in control. If you want to stop taking a drug it's your choice, of course, however, make sure you stop it in accordance with their doses, most medicines you have to ween yourself off of, especially if you have been on them a long time.
Dear seven7, If the only use of the Effexor was to control the hot flashes, they are well controlled and other problems are happening due to the medication it makes sense to reevaluate the use of the Effexor. It is best to proceed with any type of tapering with your oncologists supervision. Also making sure that your oncologist is aware of these other symptoms you are experiencing to evaluate for other problems that may be contributing to your symptoms.