The Scottish trial of adjuvant tamoxifen in node-negative breast cancer. Scottish Cancer Trials Breast Group.

This paper presents results, 5 years after closure, of a randomized trial comparing adjuvant with postrelapse tamoxifen in 747 women with histological node-negative breast cancer. Two hundred thirty-six disease-free patients on adjuvant therapy were secondarily randomly assigned at 5 years to stop or to continue tamoxifen until relapse. Adjuvant tamoxifen, taken for a median duration of 60 months, has significantly prolonged disease-free survival overall (P = .0001), in the 214 premenopausal group (P = .018), in the 533 postmenopausal group (P = .0026), and for the 246 patients with estrogen receptor levels greater than 19 fmol/mg of protein (P = .0032); distant relapse has also been delayed overall (P = .029). Total survival comparison by Kaplan-Meier life-table analysis shows a nonsignificant trend in the same direction (P = .07). Adjuvant tamoxifen has also reduced the incidence of contralateral breast cancer and of death from myocardial infarction. No increase in the incidence of endometrial cancer has been found.