Exemestane alone and sequential tamoxifen treatment followed by exemestane are appropriate therapies in postmenopausal women with hormone receptor (HR)-positive breast cancer, as confirmed by a 10-year follow-up study published in The Lancet Oncology.

Exemestane monotherapy or sequential therapy with tamoxifen and exemestane have been among the standards of therapy in treatment of HR-positive breast cancer, and previously completed 5-year follow-up studies have shown similar rates of disease-free survival (DFS), overall survival (OS), and relapse-free survival.

The phase 3 TEAM trial (ClinicalTrial.gov Identifiers: NCT00279448 and NCT00032136)  enrolled 9776 postmenopausal women with early-stage HR-positive breast cancer, and randomly assigned them 1:1 to receive oral exemestane 25 mg once daily for 5 years or sequential tamoxifen 20 mg once a day for 2.5 years followed by 2.5 years of exemestane.

The primary outcome was DFS at 10 years of follow-up, and secondary outcomes included OS, recurrence-free interval, and distant recurrence-free interval.

Of the originally enrolled 9776 patients, only 6120 were considered for the current analysis due to a lack of long term data. The median follow-up period was 9.8 years. Thirty percent of patients in the exemestane arm and 31% of those in the sequential arm had a DFS event during the 10-year follow-up period. Ten-year DFS was 67% (95% CI, 65%-69%) in both the exemestane and the sequential arms (hazard ratio [HR], 0.96; 95% CI, 0.88-1.05; P =.30).

Both the exemestane and sequential arms had 24% of patients die during the follow-up period. The 10-year OS was 74% (95% CI, 72%-75%) in the exemestane group and 73% (95% CI, 72%-75%) (HR, 0.98; 95% CI, 0.89-1.09; P = 0.74) in the sequential group.

The 10-year follow-up study of the TEAM trial shows that exemestane monotherapy and sequential tamoxifen followed by exemestane had no significant differences in DFS or OS, and are reasonable therapy strategies for the treatment of postmenopausal women with HR-positive breast cancer.

Reference

1. Derks M, Blok E, Seynaeve C, et al. Adjuvant tamoxifen and exemestane in women with postmenopausal early breast cancer (TEAM): 10-year follow-up of a multicenter, open-label, randomized, phase 3 trial. [published online July 18, 2017]. Lancet Oncol. doi: 10.1016/S1470-2045(17)30419-9