Tamoxifen rechallenge: response to tamoxifen following relapse after adjuvant chemohormonal therapy for breast cancer.

Abstract

Two-hundred seventy-three node-positive primary breast cancer patients with positive estrogen or progesterone receptors were placed on a short-term chemohormonal adjuvant program that included tamoxifen. At present, 64 have relapsed, 19 of whom have been rechallenged with tamoxifen after disease-free intervals (DFI) ranging from 0.4 to 4.4 years. Most patients had only one site of disease recurrence. Two patients have achieved complete remission (CR) and three partial remission (PR) for a CR and PR rate of 26% (95% confidence interval for CR and PR is 9% to 51%). Duration of response has ranged from 3 to 17+ months. Patients who receive short-term adjuvant therapy with tamoxifen and who relapse may respond to tamoxifen rechallenge. In this series, the response rate to tamoxifen rechallenge was similar to the response rate for patients unselected for estrogen receptor status receiving first-line endocrine therapy for breast cancer relapse.