Positron emission tomography using [F-18]fluorodeoxyglucose for monitoringprimary chemotherapy in breast cancer

Purpose: To address the role of positron emission tomography (PET) using [F -18]fluorodeoxyglucose (FDG) to monitor primary (neoadjuvant) chemotherapy in patients with locally advanced breast cancer. Patients and Methods: Quantification of regional FDG uptake of the breast a cquired after the first and second courses of chemotherapy was compared wit h the baseline scan in 22 patients with a total of 24 breast carcinomas. To evaluate the predictive value of PET imaging, histopathologic response aft er completion of chemotherapy classified as gross residual disease (GRD) or minimal residual disease (MRD) served as the gold standard. Results: Significant differences in tracer uptake between nonresponding tum ors (GRD) and responding lesions (MRD) were observed (P < .05) as early as after the first course of chemotherapy. Tracer uptake showed little change in tumors with GRD found later in pathologic analysis but decreased sharply to the background level in most tumors with MRD. After the first course, a ll responders were correctly identified (sensitivity 100%, specificity 85%) by a standardized uptake value decrease below 55% of the baseline scan. At this threshold, histopathologic response could be predicted with an accura cy of 88% and 91% after the first and second courses of therapy, respective ly. Conclusion: This study demonstrates that in patients with advanced breast c ancer undergoing primary chemotherapy, FDG-PET differentiates responders fr om nonresponders early in the course of therapy. This may help improve pati ent management by avoiding ineffective chemotherapy and supporting the deci sion to continue dose-intensive preoperative chemotherapy in responding pat ients. J Clin Oncol 18:1689-1695. (C) 2000 by American Society of Clinical Oncolog y.