Hi @Annetted. It could be a lot of things contributing to your fatigue. You've gone through the stress of a cancer diagnosis. You've had surgery. You've started oestrogen suppression medication, and you've had radiotherapy. The fatigue after radiotherapy treatment does continue to get worse for a few weeks after treatment finishes. Add the tamoxifen to that...... All the research suggests that some form of exercise actually helps with the fatigue, so that could be worth a try.
Take care
Lyn