Factors predicting the response of patients with advanced breast cancer to endocrine (Megace) therapy

We have treated 238 patients with advanced breast cancer with megestrol acetate (Megace, Bristol-Myers): 221 were assessable for response at 6 months by UICC criteria. Thirty-six (16%) patients responded, 54 (25%) were static and 131 (59%) progressed. Survival from the time of starting Megace calculated by log-rank analysis showed no significant difference in survival between patients showing response and static disease at 6 months. Patients with progression of disease within 6 months survived significantly shorter than patients who showed response or static disease at 6 months. Categorizing response at 6 months appeared to identify patients who had static disease of worthwhile duration. ER status of the primary tumour correlated significantly with survival from the time of commencing Megace. However, when Megace was used as a second-line hormone therapy the assessment of response or static disease on prior hormone therapy was a better predictor of the effect of Megace than ER status of the primary tumour.