Scottish adjuvant tamoxifen trial: a randomized study updated to 15 years

Background and Methods: The Scottish Adjuvant Tamoxifen Trial (main trial) was initiated in April 1978 to assess the effect of tamoxifen given to pati ents with breast cancer immediately after mastectomy (or mastectomy plus ra diation therapy) (adjuvant arm) or only after the patients had had a relaps e (control arm); 1323 patients were randomly assigned (667 to the adjuvant arm and 656 to the control arm). Results have been reported for the follow- up period from 2.5 through 8 years. In this article, we report updated resu lts after a median follow-up of 15 years, If agreeable and eligible, patien ts who were disease free at 5 years in the adjuvant arm of the main trial w ere entered into a duration trial and randomly assigned either to stop taki ng tamoxifen (169 patients) or to continue taking it indefinitely until rel apse or death (173 patients). For this update, we analyzed information on d eath, recurrence, survival, and other malignancies for all but 21 of the 56 0 living patients from the original and duration trials to determine the pr obabilities of total survival, systemic relapse of disease, and death from breast cancer. All statistical tests are two-sided. Results: The beneficial effect of adjuvant tamoxifen given for 5 years on the probability of total survival (P = .006), systemic relapse (P = .007), and death from breast ca ncer (P = .002) has been maintained through 15 years. No additional benefit was observed in those randomly assigned to continue taking tamoxifen beyon d 5 years. Conclusion: Information from this study suggests that, if adjuva nt tamoxifen is given to women with operable breast cancer, it need not be for more than 5 years.