This study was designed to determine whether a preoperative fluorodeoxyglucose (FDG) positron emission tomography (PET) integrated with computed tomography (CT) (FDG-PET/CT) could be used as a guide for axillary node dissection (AND) or sentinel lymph node biopsy (SNB) in breast cancer patients.
Between February 2007 and April 2008, we performed FDG-PET/CT scans in 137 biopsy-proven breast cancer patients planning to have an SNB to select patients for either AND (PET/CT N+) or SNB (PET/CT N0). In performing SNB, we also performed additional non-SNB (ADD), which was enlarged at the lower axilla.
Twenty-seven patients with positive scans underwent complete AND as a primary procedure, and 110 patients with negative scans underwent SNB + ADD. There were 8 cases of false negative scans, and no case of false positive scan. The overall sensitivity, specificity, positive predictive value, and overall accuracy of FDG-PET/CT in predicting axillary metastasis were 77.1%, 100%, 100%, and 94.2%, respectively. In a subset of 110 patients with SNB + ADD, 104 patients had histologically negative SN, and 6 patients had positive SN in frozen section. Among 110 SNB + ADD cases, there were only 8 cases (7.3%) of positive axillary basins in permanent biopsy, including two cases of late positives that had micrometastases in the SN only. Through selective SNB + ADD based on an FDG-PET/CT, we have spared 27 unnecessary SNBs (true positive scans).
FDG-PET/CT is a specific imaging modality for predicting axillary node metastasis, and allows for a selective approach to either AND or SNB. A selective SNB + ADD based on an FDG-PET/CT reduced both unnecessary SNBs and positive axillary basins, enhancing the identification rates of SN and the accuracy of SNB.