6/28/23, 12:47 AM ATLAS (tamoxifen) Pathway Feedback Search Clinical Topics Home Studies ATLAS (tamoxifen) ATLAS (tamoxifen) Trial question What are the long-term effects of continuing adjuvant tamoxifen to 10 years in women with estrogen receptor-positive breast cancer? Study design Multi-center Open label RCT Population 12894 female patients Inclusion criteria: women with estrogen receptor (ER)-positive early breast cancer who had completed 5 years of treatment with tamoxifen Key exclusion criteria: contraindications to continuation of tamoxifen, pregnancy, breastfeeding, retinopathy, need for coagulation therapy, endometrial hyperplasia, other serious toxicity attributed to tamoxifen, negligibly low risk of death from breast cancer, or presence of another life- threatening disease Interventions N=3428 extended tamoxifen use (continuation up to 10 years) N=3418 standard duration tamoxifen (stop at 5 years, with no placebo) Primary outcome Recurrent breast cancer 20.8 % 20.8 18 15.6 % 10.4 % Significant decrease 5.2 % NNT = 36 0.0 % Extended tamoxifen use Standard duration tamoxifen Significant decrease in recurrent breast cancer (18% vs. 20.8%; RR 0.84, 95% CI 0.76 to 0.94) Secondary outcomes https://web.pathway.md/studies/reclazgWls1ldPjSd 1/2 6/28/23, 12:47 AM ATLAS (tamoxifen) Pathway Significant decrease in breast cancer death (12.2% vs. 15%; RR 0.71, 95% CI 0.58 to 0.88) Significant decrease in death from any cause (18.6% vs. 21.1%; RR 0.87, 95% CI 0.78 to 0.97) Significant decrease in cumulative risk of breast cancer recurrence (21.4% vs. 25.1%; RR 0.75, 95% CI 0.62 to 0.9) Safety outcomes No significant differences in primary liver cancer, colorectal cancer, stroke. Significant differences in hospitalization due to pulmonary embolus (0.6% vs. 0.3%), ischemic heart disease (2.0% vs. 1.0%), and endometrial cancer (1.8% vs. 1.0%), cumulative risk of endometrial cancer during year 5-14 (3.1% vs. 1.6%). Conclusion In women with estrogen receptor (ER)-positive early breast cancer who had completed 5 years of treatment with tamoxifen, extended tamoxifen use was superior to standard duration tamoxifen with respect to recurrent breast cancer. Reference Davies C, Pan H, Godwin J et al. Long-term effects of continuing adjuvant tamoxifen to 10 years versus stopping at 5 years after diagnosis of oestrogen receptor-positive breast cancer: ATLAS, a randomised trial. Lancet. 2013 Mar 9;381(9869):805-16. Open reference URL https://web.pathway.md/studies/reclazgWls1ldPjSd 2/2