Late Extended Adjuvant Treatment With Letrozole Improves Outcome in Women With Early-Stage Breast Cancer Who Complete 5 Years of Tamoxifen Academic Article uri icon

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  • PURPOSE: The National Cancer Institute of Canada Clinical Trials Group MA.17 trial examined the efficacy of letrozole (LET) started within 3 months of 5 years of adjuvant tamoxifen in postmenopausal hormone receptor-positive early-stage breast cancer. When the trial was unblinded, patients who received placebo (PLAC) were offered LET. PATIENTS AND METHODS: This cohort analysis describes the outcomes of women assigned PLAC at the initial random assignment after unblinding. Efficacy outcomes of women who chose LET (PLAC-LET group) were compared with those who did not (PLAC-PLAC group) by the hazard ratios and by P values calculated from Cox models that adjusted for imbalances between the groups. Toxicity analyses included only events that occurred after unblinding. RESULTS: There were 1,579 women in the PLAC-LET group (median time from tamoxifen, 2.8 years) and 804 in the PLAC-PLAC group. Patients in the PLAC-LET group were younger; had a better performance status; and were more likely to have had node-positive disease, axillary dissection, and adjuvant chemotherapy than those in the PLAC-PLAC group. At a median follow-up of 5.3 years, disease-free survival (DFS; adjusted hazard ratio [HR], 0.37; 95% CI, 0.23 to 0.61; P < .0001) and distant DFS (HR, 0.39; 95% CI, 0.20 to 0.74; P = .004) were superior in the PLAC-LET group. More self-reported new diagnoses of osteoporosis and significantly more clinical fractures occurred in the women who took LET (5.2% v 3.1%, P = .02). CONCLUSION: Interpretation of this cohort analysis suggests that LET improves DFS and distant DFS even when there has been a substantial period of time since the discontinuation of prior adjuvant tamoxifen.


  • Goss, Paul E
  • Ingle, James N
  • Pater, Joseph L
  • Martino, Silvana
  • Robert, Nicholas J
  • Muss, Hyman B
  • Piccart, Martine J
  • Castiglione, Monica
  • Shepherd, Lois E
  • Pritchard, Kathleen
  • Livingston, Robert B
  • Davidson, Nancy E
  • Norton, Larry
  • Perez, Edith A
  • Abrams, Jeffrey S
  • Cameron, David A
  • Palmer, Michael J
  • Tu, Dongsheng

publication date

  • April 20, 2008

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