@Della, I feel for you, I have been in exactly that situation (in fact, most of us have).
I chose to go the chemo and will go the radiation but if the hormone blockers make life hard, I may discontinue them. (Ten years of hormone tablets is a lot to cope with if it really stuffs me up)
My reasons are: the Chemo will mop up anything that may be floating around in my blood or lymphatic system, the radiation will clear up any cancer that may have been left in situ and the hormone blockers will have a final go at starving any cancer that may be left after both the chemo and radiation. (as my cancer is hormone positive).
Each one will reduce my risk of the cancer returning. If any was left and it did happen to spread, it could go to the brain, liver or lungs. I figure it may take a while to recover from the nasty side effects but I'm going to fight like hell to make sure I have every chance of living my best life. I'm not going to rule out any medication that can reduce my risk cancer unless the side effects become unmanageable and I won't know that until I'm going through it and then I'll consider stopping it.
No one can make this decision for you, you need to decide what is best for you and the risks involved. To make the decision even harder, everyone reacts differently to the chemo. Some people come through fairly easily and some really do struggle and you won't know until you do it. Do you have a breast care nurse? If not you can find one here:
https://www.mcgrathfoundation.com.au/get-support/find-a-nurse/
You can discuss it with her and she'll help you weigh up the options.
Best wishes and care XXXX