- Perimenopausal patients: Patients receive tamoxifen citrate for 2-3 years and aromatase-inhibitor therapy for 2-3 years OR tamoxifen citrate for 5 years followed by aromatase-inhibitor therapy for 2-3 years (if follicle-stimulating hormone > 30 IU/L and/or estradiol < 30 ng/L).