Randomized study comparing chemotherapy with and without estrogen priming in advanced breast cancer

A randomized trial was performed to determine if combination chemotherapy (CT) with estrogen (E) priming (E+ study arm) was superior to CT alone (E- study arm) in patients with advanced breast cancer. CT for both arms included adriamycin + vincristine (AV) starting on day 7 alternating with cytoxan + methotrexate + fluorouracil (CMF) starting on day 28, the entire cycle repeated every 6 weeks. Estrogen priming consisting of 2 mg estradiol + 1 mg estriol (E+ arm) was given orally twice daily beginning on day 1 and continuously through CT until disease progression or unacceptable toxicity. Performance status (KPS) for all patients (n=19, E+ arm; n=22, E- arm) ranged between 70-100%. Mean age (53 y, E+ arm; 56 y, E- arm), menopausal and estrogen receptor status and treatment duration (approximately 38 weeks) were similar for both groups. Estrogen priming did not alter or enhance CT toxicity. Objective responses (CR,PR) were noted in 79% on the E+ arm (CR=11%, PR=68%) and in 73% on the E- arm (CR=9%, PR=64%). Thus, estrogen priming in this cohort of patients with advanced breast cancer did not appear to add to the toxicity or palliative benefit of CT.