Postmenopausal breast cancer: extended letrozole reduces recurrence

In postmenopausal patients with breast cancer who received 2–3 years of tamoxifen, treating women with an extended 5-year treatment with the aromatase inhibitor letrozole significantly improved disease-free survival (DFS) compared with the standard approach of 2–3 years of letrozole.

Prof. Lucia Del Mastro (University of Genoa, Italy) presented the results of a multicentre, open-label, randomised phase 3 trial (NCT01064635), which was simultaneously published in the Lancet Oncology [1,2]. Postmenopausal women with stage 1–3 histologically proven and operable invasive HR-positive breast cancer (n=2,056) were enrolled between 1 August 2005 and 24 October 2010 and randomly assigned to receive letrozole (2.5 mg once daily) for 2–3 years (n=1,030, as the control group), or for 5 years (n=1,026, as the “extended” group). The primary endpoint was invasive disease-free survival (IDFS) in the intention-to-treat population.

With a median follow-up of 11.7 years, DFS events occurred in 20.7% of patients in the extended group and 25.4% of patients in the control group. The 12-year DFS rates were 67% and 62%, respectively (HR 0.78; 95% CI 0.65–0.93; P=0.0064). DFS benefit did not change after multivariate Cox analysis (HR 0.79; 95% CI 0.66–0.95; P=0.014), and was consistent across subgroups. The 12-year overall survival rates were 88% in the extended group and 84% in the control group (HR 0.77; 95% CI 0.60–0.98; P=0.036).

Arthralgia (2.2% in the control vs 3.0% in the extended group) and myalgia (0.7% vs 0.9%) were the most common grade 3 and 4 adverse events. Serious treatment-related adverse events occurred in 0.3% of the control group and 0.8% in the extended group. No deaths related to toxic effects occurred.

Prof. Del Mastro concluded, "This regimen [sequential endocrine therapy with tamoxifen for 2–3 years followed by letrozole for 5 years] can be considered as one of the optimal standard endocrine treatments for postmenopausal patients with HR-positive breast cancer."

1. Del Mastro L, et al. Extended therapy with letrozole as adjuvant treatment of postmenopausal patients with early-stage breast cancer: A randomised, phase III trial of the Gruppo Italiano Mammella. Abstract 118O, ESMO Congress 2021, 16–21 September.
2. Del Mastro L, et al. Lancet Oncol. 2021;22(10):1458–67.

 

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Posted on 19 November, 2021