Newly published data in The New England Journal of Medicine affirm five-year upfront use of Femara (letrozole) following surgery as an optimal treatment approach versus tamoxifen for postmenopausal women with early stage breast cancer (hormone-receptor positive).
The data include an analysis from the Breast International Group (BIG) 1-98 trial that evaluated patients taking either a sequence of Femara and tamoxifen for five years or Femara alone (as monotherapy) for five years. Also included is the update of the Monotherapy Arms Analysis (MAA) conducted 10 years after initiation of the study, comparing five years of Femara alone versus five years of tamoxifen alone following surgery (adjuvant setting). The BIG 1-98 trial was conducted by the International Breast Cancer Study Group (IBCSG).
Results from the Sequential Treatments Analysis (STA) concluded that sequential treatment with tamoxifen and Femara in the first five years after breast cancer surgery did not improve disease-free survival compared with Femara alone for the same duration after surgery. In the 10-year MAA analysis, Femara monotherapy demonstrated significant long-term improvement of disease-free survival (P=0.03) and significant long-term reduction in risk of distant disease spread (metastasis) (P=0.05) compared with tamoxifen. In patients treated with Femara monotherapy, a non-statistically significant relative reduction in the risk of death of 13% versus tamoxifen (P=0.08) was observed.
“The BIG 1-98 study results suggest survival benefit with five years of letrozole therapy after surgery compared to tamoxifen for the same time period following surgery, confirming the benefit of initial use of letrozole in the adjuvant breast cancer setting,” saidHenning T Mouridsen, Professor of Oncology, Copenhagen University Hospital and BIG 1-98 investigator. “Letrozole is the only aromatase inhibitor versus tamoxifen to demonstrate early and significant reduction in the risk of distant metastases, significant improvement in disease-free survival and this suggestion in overall survival benefit in primary breast cancer patients.”