I just wanted to mention my experience with Tamoxifen, because it is not all that uncommon, but often people don't take the time to write about when things are going well. I was on Tamoxiffen for 4.5 years before I switched to Exemestane ( I was pre-menopausal when I was diagnosed but once I was post menopausal I was switched to an AI - Aromatase Inhibitor) In the time I was on Tamoxifen, I rarely had any side effects. The occasional hot flash - maybe 6 a year, and the occasional ankle swelling. That's it.
I wish you well with your radiation and as you continue with the Herceptin.
Keep us posted how you are doing