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Table 6 Clinical trials testing tamoxifen beyond 5 years

From: Status of adjuvant endocrine therapy for breast cancer

Study Number Population Arms Disease-free survival hazard ratio (95% CI) Overall survival hazard ratio (95% CI)
ATLAS [113] Open-label 6,846a Pre- and post-menopausal women with ER+ EBC who already received T for 5 years (in the context of ATLAS trial total number = 12,894) T for additional 5 years (10 years) versus stop T (5 years) 5-9 years RR 0.90 (0.79-1.02) P = 0.10 > 10 years RR 0.75 (0.62-0.90) P = 0.01 BC mortality: 5-9 years RR 0.97 (0.79-1.18) P = 0.74 BC mortality: >10 years RR 0.71 (0.58-0.88) P = 0.002
     All years log-rank = 0.002  
     Absolute reduction at years 15: 3.7%  
aTToM [114]b Open-label 6,953 Invasive EBC who had already been taking T for 5 years. 2,755 ER+ (39%) and 4,198 ER untested (61%) (estimated 80% ER+ if status unknown) T for additional 5 years versus no further treatment RR 0.85 (0.76-0.95) P = 0.003 BC mortality: 5-9 years RR 1.08 (0.85-1.38)
     Absolute reduction 4% BC mortality: >10 years RR 0.75 (0.63-0.90) P = 0.007 BC mortality: all years RR 0.88 (0.74-1.03) P = 0.1
Pooled analysis ATLAS + aTToM [114]b 17,477 10,543c ER+ from ATLAS plus 6,934 ER+ from aTTom T 10 versus 5 years NA BC mortality: 5-9 years RR 0.97 (0.84-1.15)
      BC mortality: >10 years RR 0.75 (0.65-0.86) P = 0.00004
      BC mortality: all years RR 0.85 (0.77-0.94) P = 0.001
  1. aAnalysis of estrogen receptor-positive (ER+) patients only; bfigures are derived from the abstract [114] and the presentation at American Society of Clinical Oncology meeting 2013 available online; cIPCW (inverse probability of censoring weighted) estimate of the effect in ER+. ATLAS, Adjuvant Tamoxifen: Longer Against Shorter; aTToM, Adjuvant Tamoxifen-To Offer More?; BC, breast cancer; CI, confidence interval; EBC, early breast cancer; RR, rate ratio; T, tamoxifen.