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Title: Significant Reduction in Death and Recurrence Seen in Women Receiving Letrozole for Breast Cancer: Presented at ASCO

"Significant Reduction in Death and Recurrence Seen in Women Receiving Letrozole for Breast Cancer: Presented at ASCO"

By Cameron E. Johnston ORLANDO, FL -- May 18, 2005 -- The latest analysis of data from the Breast Cancer International Study Group (BIG I-98) shows significant reductions in cancer-related deaths and in the risk of metastasis among postmenopausal women treated with the aromatase inhibitor letrozole (Femara) compared with tamoxifen. The results of the study were presented here May 15[^th at the American Society of Clinical Oncology Annual Meeting (ASCO), and were discussed in a press conference on May 13^th by principal investigator Beat Thurlimann, MD, senior lecturer in oncology, University of Bern, Bern, Switzerland, and chairman of the International Breast Cancer Study Group.

The BIG-I98 study divided women into 4 treatment arms -- tamoxifen alone for 5 years, letrozole alone for 5 years, tamoxifen for 3 years followed by letrozole for 2 years, or letrozole for 3 years followed by tamoxifen for 2 years.

Women had already completed courses of either radiation or chemotherapy or had surgery, or a combination of these treatments.

Dr. Thurlimann said BIG-I98 is the largest ongoing study of women with breast cancer who are being treated with letrozole. It involves more than 8000 women in 27 countries and will continue to be analyzed at least until 2008, she said.

After a median follow-up of 28 months, the risk of recurrence or death was 19% lower in the letrozole group than in the tamoxifen group. The risk of cancer metastasis in the letrozole group was reduced by 27% compared with tamoxifen.

At 3 years of follow-up, the cumulative incidence of recurrence was 6.2% in the letrozole group and 8.1% in the tamoxifen group. At 5 years, the cumulative incidence of recurrence was 10.2% in the letrozole group and 13.6% in the tamoxifen group.

Overall, the difference in 5-year outcomes represents an absolute risk reduction of 3.4%, which was highly statistically significant.

Major differences in side effects included more joint pain in the women using letrozole, which was not unexpected, and significantly more women developed hyperlipidemia as well. "Tamoxifen alone lowers LDL cholesterol by 10-15%, so at least part of this difference in hyperlipidemia is due to that we call the tamoxifen effect," Dr. Thurlimann said.

A total of 166 women in the letrozole group and 196 in the tamoxifen arm died during the study period.

"Tamoxifen is not obsolete, but its role in breast cancer treatments is likely to become limited as studies continue to show that aromatase inhibitors are more effective for many patients with the disease," he said.

[Presentation title: BIG 1-98: Randomized Double-Blind Phase III Study to Evaluate Letrozole (L) Vs. Tamoxifen (T) as Adjuvant Endocrine Therapy for Postmenopausal Women With Receptor-Positive Breast Cancer. Abstract 511]

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