SAN ANTONIO—Results of two randomized International Breast Cancer Study Group (IBCSG) trials of chemoendocrine therapy for node-negative breast cancer suggest that adjuvant chemotherapy may provide additional benefit over endocrine therapy alone for patients with estrogen-receptor (ER)-negative, but not ER-positive, tumors.
Endocrine responsiveness is an important determinant of treatment response for both premenopausal and postmenopausal patients, according to the studies presented at the 25th Annual San Antonio Breast Cancer Symposium (abstract 11).
The two trials—IBCSG VIII and IBCSG IX—were conducted between 1988 and 1998. Patients in both trials had histologically proven unilateral breast cancer, stage T1a, 1b, 2a, T2, or T3, with negative nodes and no metastases. Tumors could be either ER positive or negative; an unknown designation was permitted only in the absence of material.
The trial results were reported by Monica M. Castiglione-Gertsch, MD, director of the Swiss Institute for Applied Cancer Research Coordinating Center in Bern, Switzerland, and chief executive officer of the IBCSG.
For IBCSG VIII, 1,109 premenopausal or perimenopausal women were randomized to goserelin(Drug information on goserelin) (Zoladex) 3.6 mg subcutaneously monthly for 24 months; classical CMF (oral cyclophosphamide(Drug information on cyclophosphamide) at 100 mg/m2 on days 1 to 14; IV metho-trexate at 40 mg/m2 on days 1 and 8; and IV fluorouracil(Drug information on fluorouracil) at 600 mg/m2 on days 1 and 8) for six courses; or classical CMF for six courses followed by goserelin for 18 months. Median follow-up was 5.7 years.
IBCSG IX randomized 1,669 postmenopausal women to tamoxifen(Drug information on tamoxifen) (Nol-vadex) alone (20 mg/d for 60 months) or classical CMF followed by tamoxifen (20 mg/d) for 57 months. Median follow-up was 6 years.
Endocrine Responsiveness
