What endocrine therapy would you recommend for a perimenopausal female with a low risk Oncotype, HR+, HER2-negative, SLNB negative breast cancer who is clinically postmenopausal but with FSH, LH and estradiol that are not in the postmenopausal range?  

In this situation, with a low risk, node-negative disease with ambivalent menopausal status, Tamoxifen, unless contraindicated, would be my choice. A SERM is equally effective for premenopausal and postmenopausal women. In the course of adjuvant endocrine therapy, changing to an aromatase inhibitor ...