North American Adjuvant Breast Cancer Trials

The National Cancer Institutes in the United States and Canada sponsor Cooperative Groups to perform randomized trials in distinct subsets of patients with early breast cancer. In women with low-risk ductal carcinoma in situ (DCIS), ongoing studies are evaluating the role of adjuvant breast irradiation. For those with low-risk, node-negative invasive tumors, efforts have been directed to improving the efficacy of tamoxifen, while in high-risk patients the focus has been on improving chemotherapy. The roles of dose intensity and dose density have been evaluated at dose levels requiring either G-CSF or stem cells. More recently, the introduction of taxanes into adjuvant regimens has been a major area of investigation. Following treatment with doxorubicin-cyclophosphamide (AC), patients have been randomized to receive paclitaxel or no further therapy in INT 0148 and NSABP B-28 and to receive docetaxel in NSABP B-27. For women with 4-9 involved nodes, sequential treatment A(doxorubicin)-T(paclitaxel)-C(cyclophosphamide) with G-CSF is being compared to AC x 4 followed by high-dose chemotherapy with stem cell support. Cooperative Group trials have been critical in defining the standard of care in the past, and successful completion of these new trials is essential for further progress against breast cancer.