@slonimski
Your Medical Onc is the one who should be advising you on the Hormone Blockers, not your Rad Onc .... I didn't start mine til after I'd finished my 4 weeks of Rads ....
Aromatase inhibitors (Letrozole, Exemestane and Anastrozole) are usually more effective than tamoxifen in postmenopausal women ... so your age & 'stage' of menopause is all a part of deciding which meds you'll end up on.
take care