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.
ASJC Scopus subject areas
- Cancer Research
Late extended adjuvant treatment with letrozole improves outcome in women with early-stage breast cancer who complete 5 years of 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 I.; Livingston, Robert B; Davidson, Nancy E.; Norton, Larry; Perez, Edith A.; Abrams, Jeffrey S.; Cameron, David A.; Palmer, Michael J.; Tu, Dongsheng.In: Journal of Clinical Oncology, Vol. 26, No. 12, 2008, p. 1948-1955.
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