Comparison of the systemic and intratumoral effects of tamoxifen and the aromatase inhibitor vorozole in postmenopausal patients with primary breast cancer.

Purpose: To determine biologic differences, if any, between presurgical endocrine treatment with an aromatase inhibitor (vorozole) and tamoxifen in patients with postmenopausal primary breast cancer.

Patients And Methods: Randomization was to 12 weeks of 2.5 mg of vorozole per day or 20 mg of tamoxifen per day, both orally.

Vorozole results in greater oestrogen suppression than formestane in postmenopausal women and when added to goserelin in premenopausal women with advanced breast cancer.

The high potency and selectivity of new aromatase inhibitors has translated to greater efficacy and improved tolerability in comparison with established second-line hormonal agents for advanced breast cancer in phase III clinical trials. Two pharmacological studies are reported which assess the use of one of these inhibitors, vorozole, in combination or comparison with well-established methods of oestrogen deprivation in pre and postmenopausal patients. When combined with the gonadotrophin-releasing hormone agonist (GnRHa) goserelin in 10 premenopausal patients, vorozole markedly enhanced the suppression of serum levels of oestrone, oestradiol and, oestrone sulphate beyond that achieved by goserelin alone (by a mean 74%, 83%, and 89%, respectively).