Randomized Trial Of 2 Vs. 5 Years Of Adjuvant Tamoxifen In Postmenopausal Women With Early-Stage Breast Cancer

The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 20, 1996

Lars E. Rutqvist, M.D., Ph.D., director, Oncology Center, Karolinska Hospital (Stockholm, Sweden), presented the results of a study which aimed to determine the optimal duration of tamoxifen treatment for early-stage breast cancer patients.

Adjuvant treatment with tamoxifen in some patients with early-stage breast cancer has conclusively been shown to decrease the risk of disease recurrence andto improve survival. However, the optimal duration of treatment remains controversial. The most commonly used schedules involved treatment with tamoxifen for two years. Preclinical data suggest that the benefit with tamoxifen may be greater with a more prolonged treatment period. On the other hand, long-term treatment may also be associated with side effects such as an increased risk of tamoxifed-induced endometrial cancer.

In 1983, the Swedish Breast Cancer Cooperative Group initiated a randomized multicenter trial of adjuvant, postoperative treatment with tamoxifen for two years versus five years in postmenopausal women with primary breast cancer. During 1983 through 1991, a total of 3,900 women were included in the study.

At the median follow-up of 5 1/2 years, there was a statistically significant (18%) reduction of disease recurrences and an improved overall survival among those women who had been treated wth tamoxifen for five years. After 10 years, the overall survival was 74% among patients who were treated with tamoxifen for two years compared with a survival rate of 80% amond the patients who were treated with tamoxifen for five years.

"This is the first randomized trial providing statistically reliable evidence of benefit with adjuvant tamoxifen for longer than the standard two years," Patricia Braly, M.D., professor and chief, Department of Obstetrics and Gynecology, LSU Medical Center (New Orleans, LA), said at a press briefing today. "The study results show that five years of adjuvant tamoxifen should be standard treatment for all post-menopausal patients with invasive breast cancer who have estrogen receptor positive disease."