Extending Aromatase-Inhibitor Adjuvant Therapy to 10 Years.

BACKGROUND: Treatment with an aromatase inhibitor for 5 years as up-front monotherapy or after tamoxifen therapy is the treatment of choice for hormone-receptor-positive early breast cancer in postmenopausal women. Extending treatment with an aromatase inhibitor to 10 years may further reduce the risk of breast-cancer recurrence. METHODS: We conducted a double-blind, placebo-controlled trial to assess the effect of the extended use of letrozole for an additional 5 years. Our primary end point was disease-free survival. RESULTS: We enrolled 1918 women. After a median follow-up of 6.3 years, there were 165 events involving disease recurrence or the occurrence of contralateral breast cancer (67 with letrozole and 98 with placebo) and 200 deaths (100 in each group). The 5-year disease-free survival rate was 95% (95% confidence interval [CI], 93 to 96) with letrozole and 91% (95% CI; 89 to 93) with placebo (hazard ratio for disease recurrence or the occurrence of contralateral breast cancer, 0.66; P=0.01 by a two-sided log-rank test stratified according to nodal status, prior adjuvant chemotherapy, the interval from the last dose of aromatase-inhibitor therapy, and the duration of treatment with tamoxifen). The rate of 5-year overall survival was 93% (95% CI, 92 to 95) with letrozole and 94% (95% CI, 92 to 95) with placebo (hazard ratio, 0.97; P=0.83). The annual incidence rate of contralateral breast cancer in the letrozole group was 0.21% (95% CI, 0.10 to 0.32), and the rate in the placebo group was 0.49% (95% CI, 0.32 to 0.67) (hazard ratio, 0.42; P=0.007). Bone-related toxic effects occurred more frequently among patients receiving letrozole than among those receiving placebo, including a higher incidence of bone pain, bone fractures, and new-onset osteoporosis. No significant differences between letrozole and placebo were observed in scores on most subscales measuring quality of life. CONCLUSIONS: The extension of treatment with an adjuvant aromatase inhibitor to 10 years resulted in significantly higher rates of disease-free survival and a lower incidence of contralateral breast cancer than those with placebo, but the rate of overall survival was not higher with the aromatase inhibitor than with placebo. (Funded by the Canadian Cancer Society and others; ClinicalTrials.gov numbers, NCT00003140 and NCT00754845.).

Quality of Life From Canadian Cancer Trials Group MA.17R: A Randomized Trial of Extending Adjuvant Letrozole to 10 Years.

Purpose MA.17R was a Canadian Cancer Trials Group-led phase III randomized controlled trial comparing letrozole to placebo after 5 years of aromatase inhibitor as adjuvant therapy for hormone receptor-positive breast cancer. Quality of life (QOL) was a secondary outcome measure of the study, and here, we report the results of these analyses. Methods QOL was measured using the Short Form-36 (SF-36; two summary scores and eight domains) and menopause-specific QOL (MENQOL; four symptom domains) at baseline and every 12 months up to 60 months. QOL assessment was mandatory for Canadian Cancer Trials Group centers but optional for centers in other groups. Mean change scores from baseline were calculated. Results One thousand nine hundred eighteen women were randomly assigned, and 1,428 women completed the baseline QOL assessment. Compliance with QOL measures was > 85%. Baseline summary scores for the SF-36 physical component summary (47.5 for letrozole and 47.9 for placebo) and mental component summary (55.5 for letrozole and 54.8 for placebo) were close to the population norms of 50. No differences were seen between groups in mean change scores for the SF-36 physical and mental component summaries and the other eight QOL domains except for the role-physical subscale. No difference was found in any of the four domains of the MENQOL Conclusion No clinically significant differences were seen in overall QOL measured by the SF-36 summary measures and MENQOL between the letrozole and placebo groups. The data indicate that continuation of aromatase inhibitor therapy after 5 years of prior treatment in the trial population was not associated with a deterioration of overall QOL.