Comparing Anastrozole-Placebo to the Combination Anastrozole-ZD1839 in Postmenopausal Patients with Estrogen Receptor and/or Progesterone Receptor Metastatic Breast Cancer

This study is being carried out to see if treatment with ZD1839 (Gefitinib) combined with Arimidex (Anastrozole) has improved efficacy over Arimidex alone in preventing progression of metastatic breast cancer.

This is a phase II, multicenter, double-blind, randomized, placebo-controlled trial. Patients will be randomized in a double-blind manner in a 1:1 ratio to receive either 250 mg/day ZD1839 or matched placebo in combination with 1 mg/day anastrozole. The dose of ZD1839 has been selected based on clinical studies in other tumor types suggesting identical efficacy together with a better toxicity profile in patients treated at 250 mg compared to 500 mg/day. The 1 mg dose of anastrozole is the standard approved dose.