Recent results of an ongoing study show that the drug Femara (generic name letrozole) may be more effective at treating early-stage breast cancer in post-menopausal women than the standard drug, tamoxifen (brand name, Nolvadex). According the study of more than 8,000 participants, post-menopausal women treated with Femara had a 19% reduced risk of relapsing and a 27% reduced risk that breast cancer would spread to other body organs, compared with those treated with tamoxifen. The study is being conducted by researchers of the International Breast Cancer Study Group, a non-profit group, in 27 countries. Financial support for the study was provided by Novartis, the manufacturer of Femara.

Results at the 26-month point in the Breast International Group (BIG) I-98 trial were presented in late January at the Primary Therapy of Early Breast Cancer 9th International Conference in St. Gallen, Switzerland. "We now have an additional tool to improve the outcome for post-menopausal women with hormone sensitive breast cancer. Together with optimal surgery, followed by chemotherapy and radiotherapy if needed, incorporation of letrozole [Femara] in the treatment plan is a step forward in the patients’ way of remaining disease from cancer. Further investigations and longer follow-up are necessary to optimize the use of letrozole [Femara] in order establish long-term safety and tolerability of the drug and to further improve its treatment benefits," said BIG 1-98 Trial study chair, Dr. Thürlimann, in an International Breast Cancer Study Group news release.

In the study, Femara was effective in women with early-stage estrogen-receptor positive breast cancer. Early-stage breast cancer is cancer that has not spread past the breast and/or underarm lymph nodes. Most early-stage breast cancer patients undergo surgery as may also receive radiation and/or chemotherapy. About 80% of breast cancer cases are estrogen sensitive, meaning that the cancer cells depend on estrogen for survival and reproduction. Tamoxifen is also indicated for estrogen sensitive breast cancers.

The BIG I-98 trial is the first of its kind to directly compare Femara and tamoxifen in post-menopausal women with early-stage breast cancer during the first five years after surgery. The study is ongoing and comparing the following:

• Five years of tamoxifen versus five years of Femara;
• Tamoxifen for two years followed by Femara for three years
• Femara for two years followed by tamoxifen for three years

According to International Breast Cancer Study Group, patients on Femara and tamoxifen experienced different side effects.

Women given tamoxifen were more likely to experience:

• Serious blood clots including deep vein thrombosis and embolism
• Vaginal bleeding, more often leading to abnormalities in the endometrial (uterine) lining which resulted in more frequent endometrial biopsies

Women given Femara were more likely to experience:

• bone fractures
• Increases in cholesterol levels, though typically mild.

Both groups of patients experienced slightly more heart attacks and strokes on the drugs, though these events were very rare with both treatments.

The researchers caution that study results involving long periods of follow-up are needed to better understand the long-term safety and effectiveness of Femara in treating early-stage breast cancer. They are currently continuing the BIG I-98 trial.

Additional Resources and References

• The January 26, 2005 International Breast Cancer Study Group news release, "Letrozole Reduces the Risk of Post-Surgery Recurrence Of Early Breast Cancer When Compared with Tamoxifen, Study Shows," was posted at http://www.ibcsg.org/index.shtm
• The January 26, 2005 Novartis news release, "First Results of Major Study Show That Femara Provides a Disease Free Survival Advantage vs. Tamoxifen in Adjuvant Treatment of Early Breast Cancer," was posted at http://www.novartis.com/
• To learn more about drugs used to treat breast cancer, please visit http://www.imaginis.com/breasthealth/bc_drugs.asp