ORLANDO, Fla., May 13 /PRNewswire/ -- Initial treatment with letrozole offers significantly greater post-surgery protection against breast cancer recurrence than does tamoxifen, in postmenopausal women with early breast cancer (19% less risk of recurrence, p=0.003) according to newly updated results of the Breast International Group 1-98 trial. In addition, the data showed letrozole reduced the risk of cancer spreading to other parts of the body (distant metastases) by 27% (p=0.0012).
"In our study, letrozole out-performed tamoxifen in a number of critical endpoints, among them reducing both the risk of recurrence and the risk of distant metastases in postmenopausal women with hormone sensitive early breast cancer," says PD Dr. Beat Thuerlimann, St. Gallen, Switzerland, BIG 1-98 Trial Study Chair. "These results are likely to have a major impact on the way early breast cancer is treated in this population."
BIG 1-98 is the only clinical trial designed to incorporate both a head-to-head comparison of letrozole with tamoxifen and a sequencing of both agents, during the first 5 years following breast cancer surgery to determine the most effective approach to minimizing the risk of breast cancer recurrence. The data presented at ASCO relates to the primary treatment comparison of initial tamoxifen versus initial letrozole at a median of 26 months follow-up. Results of the sequencing comparison will be available in 2-3 years.
Methods and Results
BIG 1-98 is a multinational Phase III double-blind, randomized multi-center trial being conducted in 27 countries and involves more than 8,000 postmenopausal women with early breast cancer who have hormone receptor-positive tumors. A primary goal of the study is to determine if letrozole could reduce the risk of a disease-free survival events (defined to include breast cancer relapse, occurrence of a second [non-breast] malignancy or death without recurrence) compared with tamoxifen. Results reported represent a median follow-up of 26 months. Among the 4,003 patients in the letrozole group, 84.0% are projected to remain alive and disease-free at 5 years compared with 81.4% of the 4,007 patients in the tamoxifen group.
There was also a difference in the pattern of side effects between letrozole and tamoxifen.
* More common on tamoxifen were:
-- venous thrombosis and embolism (clots)
-- vaginal bleeding
-- endometrial abnormalities (changes in the lining of the womb); and
-- endometrial biopsies.
* More common on letrozole were:
-- bone fractures
-- elevation of cholesterol, though this was usually mild.
Heart attacks and strokes occurred slightly more often on letrozole, though these events were very rare with both treatments.
The study is being conducted under the aegis of the Breast International Group (BIG), and is coordinated and managed by the International Breast Cancer Study Group (IBSCG). Novartis, the producer and distributor of letrozole (Femara(R)) gave financial support. The IBSCG is an active member of the BIG organization.
About Early Breast Cancer
Early breast cancer (EBC) is defined as cancer that is localized to breast tissue and/or nearby lymph nodes. Worldwide, about 800,000 women are diagnosed with EBC each year. Primary therapy for EBC usually involves surgery to remove the tumor and surrounding tissue. Standard post-surgery therapy (adjuvant) typically includes radiation and/or chemotherapy, followed if the tumor is hormone-receptor positive by endocrine treatment with 5 years of tamoxifen, which has been for decades the standard of care for postmenopausal women.
About The International Breast Cancer Study Group
The International Breast Cancer Study Group (IBSCG) is a non-profit organization founded (as the "Ludwig Breast Cancer Study Group") in 1977. It is a cooperative group that has conducted numerous high quality and important clinical trials of adjuvant therapy for patients with operable breast cancer over more than 27 years. With its network of investigators spanning five continents, the IBCSG has always been dedicated to innovative clinical research designed to improve the outcome of women with breast cancer.
About The Breast International Group
The Breast International Group (BIG) is an international non-profit organization established under Belgian law. As a communications network rather than a clinical research group in the traditional sense, BIG brings its members -- cooperative groups based in Europe, Australasia, Latin America and Canada that have affiliated centers around the world - together in an organized way to collaborate in the design, conduct and interpretation of clinical trials in EBC.
Additional information regarding BIG 1-98 and IBCSG can be found on the Web site http://www.ibcsg.org/ .
Contact persons: Rum Ekhtiar Nadia Munarini, PhD Ruder Finn IBCSG Phone: +1.212.593.5821 Phone: +41.31.389.92.27 Mobile: +1.917.331.1690 Mobile: +41.79.207.45.82
The International Breast Cancer Study GroupCONTACT: Rum Ekhtiar of Ruder Finn, +1-212-593-5821, mobile,+1-917-331-1690, for The International Breast Cancer Study Group; NadiaMunarini, PhD, of IBCSG +41-31-389-92-27, mobile, +41-79-207-45-82
Web site: http://www.ibcsg.org/
