Estrogen is produced by your adrenal gland and ovaries do even with a hysterectomy a form of estrogen blocker will be prescribed if you had a estrogen positive tumor. Tamoxifen is usually prescribed for women who have not gone through menopause. Femara and arimidex are usually prescribed for women who are menopausal
If you have hormone positive cancer, you need something to block that. Tomoxifin is used for premenopausal women & arormatase is for post menopausal women. Even if you have a hysterectomy, your body produces hormones.