TAMOXIFEN AS INITIAL ENDOCRINE THERAPY FOR METASTATIC BREAST-CANCER -LONG-TERM FOLLOW-UP OF 2 PIEDMONT-ONCOLOGY-ASSOCIATION (POA) TRIALS

Purpose: To examine the outcomes of endocrine naive patients treated w ith tamoxifen as initial endocrine therapy for metastatic breast cance r. Data were obtained from the long-term follow-up of two previously p ublished randomized trials. Patients and methods: All patients receive d tamoxifen 20 mg po in a single daily dose. Eligibility required pati ents to be age greater than or equal to 18, performance status 0-3, an d estrogen or progesterone receptor positive or unknown. Patients were ineligible if they had any prior endocrine therapy in either the adju vant or metastatic setting. Results: 156 patients have been followed f or a median of 8.3 years. Median age was 61 years, 83% were greater th an or equal to 50 years, 84% performance status of 0-1, 43% were both ER and PR positive, 33% had prior chemotherapy, 62% had a disease-free interval of >2 years, and 59% had only one metastatic site. The compl ete (14%) and partial (6%) response rate for 147 evaluable patients wa s 20% (95% CI for CR + PR of 14-27%). Multivariate analysis revealed t hat improved response was related to soft tissue involvement and posit ive PR status. The majority of patients with soft tissue, nodal or lun g metastases had responses noted within three months. Median time to d isease progression was 6.7 months. Multivariate analysis revealed that older patients, those with one metastatic site and those with positiv e PR status had the longest time to progression. Median survival was 2 7.2 months. Better performance status, fewer metastatic sites and bein g PR positive were associated with significantly improved survival. Co nclusion: The patient population in this series is not likely to be st udied in future trials because of the wide use of tamoxifen in the adj uvant setting. In a small percentage of patients with metastatic breas t cancer, tamoxifen therapy is associated with prolonged remission and survival. Pretreatment characteristics can help identify such patient s.