Extended therapy with letrozole for 5 years improves survival outcomes in postmenopausal patients with hormone positive early-stage breast cancer.

This study compared the effectiveness and safety of extended therapy with letrozole (LET; Femara) for 5 years versus the standard therapy of 2-3 years for the treatment of postmenopausal women with early-stage breast cancer (BC). The data showed that extended treatment with LET for 5 years significantly improved the survival outcomes in these patients.

BC is classified into different subtypes depending on the presence or absence of certain receptors (proteins found on the surface of the cancer cells). HR+ and HER2- BC tests positive for the estrogen and/or progesterone receptor (female sex hormones) and negative for the HER2 protein. This type of cancer accounts for 70% of all BCs. Patients with this subtype of BC commonly receive hormone therapy which acts by decreasing the female hormones.

Aromatase inhibitors like LET are a type of hormonal therapy that works by lowering estrogen production and is used for treating BC in postmenopausal women. The benefit of extending hormonal therapy beyond 5 years in patients who received tamoxifen (Nolvadex) is controversial. However, the effectiveness and safety of extended therapy with LET for 5 years versus the standard therapy of 2-3 years of LET for the treatment of postmenopausal patients with early-stage BC remains under investigation.

This study involved 2056 postmenopausal women with early-stage BC who were previously treated with tamoxifen (Nolvadex). Patients were randomly divided into 2 groups. Group 1 included 1030 patients who received LET for 2-3 years. Group 2 included 1026 patients who received LET for 5 years. The average follow-up time was 11.7 years.

After 12 years, 62% of the patients in group 1 were alive and disease-free compared to 67% of the patients in group 2. Patients in group 2 were 22% more likely to survive without any signs of cancer than patients in group 1.  

The 12-year overall survival rate was 84% in group 1 compared to 88% in group 2. Patients in group 2 were 23% more likely to have a better survival than patients in group 1.

The most common side effects were joint pain (2.2% in group 1 vs 3% in group 2) and muscle pain (0.7% in group 1 vs 0.9% in group 2).

This study concluded that extended treatment with 5 years of LET significantly improved the survival outcomes compared with the standard 2–3 years in tamoxifen-treated postmenopausal women with HR+, HER2- early-stage BC.

The patients in this study know which treatment were receiving. This may have affected the results. This study was only conducted at institutions in Italy. This study was funded by Novartis, the manufacturers of LET.