The optimal duration of hormone therapy for post menopausal patients with early breast cancer

This study aimed to compare the benefits of taking letrozole for 2.5 years versus 5 years in post-menopausal patients with early stage breast cancer. This study found no benefit of five years extended therapy with letrozole compared to 2.5 years, after an initial five years of hormone therapy. 

Breast cancer is classified into different subtypes depending on the presence or absence of certain receptors (proteins found on the surface of the cancer cells). These subtypes influence treatment options, and also directly affect disease prognosis. Hormone receptor positive cancer grows in response to female hormones such as estrogen.

Breast cancer patients with hormone receptor positive cancers commonly receive hormone treatment after initial surgery or radiotherapy. This treatment can include tamoxifen (Nolvadex) or aromatase inhibitors (for example, letrozole [Femara]). Patients take initial aromatase inhibitor treatment for five years initially but can extend this treatment for years afterwards. The ideal length of time to take hormone therapy, after the first five years, is unclear. 

This study compared different timelines of taking hormone therapy. 1824 post-menopausal patients were assigned to take letrozole for 2.5 or 5 years after initial hormone therapy. 

This study found that disease-free survival, time to metastases (spread) and overall survival (time from treatment until death from any cause) were not statistically different in patients who had taken letrozole for 2.5 or 5 years. There were fewer second primary breast cancers noted in the patients who were in the 5 year group (1.1%) compared to 2.5 years 3.1%.

This study found no benefit of five years extended therapy with letrozole versus 2.5 years, after an initial five years of hormone therapy.