International Breast Cancer Study Group trials.

Abstract

The International Breast Cancer Study Group (IBCSG) was established in 1978 as the Ludwig Breast Cancer Study Group. It involved member institutions from Switzerland, Australia, New Zealand, Sweden, Italy, Slovenia, South Africa, Spain, Canada, Hong Kong and at various times from other countries. It has completed seven trials in three generations, and has a further eight trials currently open. Total accrual to December 1997 exceeds 12,000, and more than 9000 of these patients are in active follow-up. Early trials established the pattern of addressing important biological questions and adapting the randomisation to the risk group of the patient. The first two generations of trials demonstrated that combined modality chemoendocrine therapy was superior to endocrine therapy alone or no therapy in node-positive postmenopausal patients; that a single perioperative cycle improved disease-free survival (DFS) in node-negative patients, but was inferior to more prolonged therapy in node-positive patients; and that six conventionally timed cycles of CMF were as effective as seven cycles commenced in the perioperative period. Recently reported trials in node-positive patients showed that three early cycles of CMF chemotherapy added to tamoxifen in postmenopausal patients, while late reintroduction of chemotherapy appeared detrimental, particularly in patients with ER-negative tumors. In premenopausal patients six initial cycles were superior to three, especially in younger patients. Current studies in node-positive patients are addressing the role of a gap between courses of different chemotherapy, and the relative value of the anti-estrogens tamoxifen and toremifene. In node-negative premenopausal patients ovarian suppression with goserelin is being tested either instead of or added to CMF, while the value of initial CMF before tamoxifen is being tested in node-negative postmenopausal patients. For high-risk patients a triple-transplant regimen is being compared with conventional dose therapy. Planning for future trials recognises the need for rapid accrual of large numbers of similar patients, and therefore the need for inter-Group collaboration. The emergence of the Breast International Group as a consortium of European, Australasian and Canadian cooperative Groups is important to the rapid evaluation of new agents and strategies.