The Cancer and Leukemia Group B (CALGB) was founded in 1956 and is now "a national network including 26 university medical centers, over 225 participating community hospitals and more than 3,000 oncology specialists who collaborate in clinical research studies aimed at reducing the morbidity and mortality from cancer, relating the biological characteristics of cancer to clinical outcomes and developing new strategies for the early detection and prevention of cancer."1
CALGB investigators have designed and conducted a number of pivotal clinical trials addressing treatment of breast cancer. CALGB is a member of the Breast Cancer Intergroup of North America where it regularly leads and participates in Intergroup trials. This chapter highlights trials led by the CALGB.
CALGB trials have addressed systemic therapy questions in breast cancer patients including optimum total dose of drug, schedule of drug delivery and dose density, combination versus sequential administration of different agents, as well as assessment of different agents. Many CALGB trials incorporate a factorial design in which patients are randomized into 2 or more arms for the first portion of treatment and then undergo a second randomization to 2 or more different arms for the second part of treatment. This approach allows testing of multiple hypotheses within the same trial.
CALGB has consistently had a strong correlative science program with companion laboratory studies that collect tissue, blood, and data from patients on trial to address mechanism of response, predictors of response, and other questions. For example, a correlative science study assessed different methods for assessment of HER-2 overexpression, and demonstrated fluorescence in situ hybridization (FISH) was a reliable method for measuring HER-2 expression.
A series of CALGB trials addressed questions of total dose of chemotherapy, dose density of chemotherapy delivery, and administration of agents sequentially versus in combination for early stage breast cancer.
By 1985, the NIH Consensus Conference concluded that the use of chemotherapy in node-positive premenopausal women was standard of care, while the efficacy of chemotherapy in node-positive postmenopausal women was unclear, although some studies suggested a benefit.2 Building on this basic belief, the CALGB worked to further clarify the role of adjuvant chemotherapy.
CALGB 8541: Dose and Dose Intensity of Adjuvant Chemotherapy for Stage II, Node-Positive Breast Carcinoma
CALGB 8541 addressed 2 main questions regarding CAF chemotherapy in both pre- and postmenopausal women with node-positive breast cancer. The impact of dose of drug administered per cycle was assessed using 3 different doses. The impact of dose density versus duration of treatment was also addressed as 2 of the arms administered the same total amount of drug, one over 6 cycles and the other in only 4 cycles with a higher dose per cycle.
Patients were randomized to 1 of 3 regimens of cyclophosphamide, doxorubicin, and fluorouracil (CAF):
- Group 1 (high dose) 600/60/600 mg/m2 IV every 28 days ...