- Patients with hormone receptor positive breast cancer as defined above must receive at least 5 years of adjuvant hormonal therapy in the form of tamoxifen or an aromatase inhibitor, alone or in combination with ovarian suppression. (NOTE: for patients with ER and PR staining in less than 5% of cells, hormonal therapy for at least 5 years is strongly recommended but not required). Hormonal therapy can be initiated prior to or during protocol therapy.