Determination of indication for sentinel lymph node biopsy in clinical node-negative breast cancer using preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography fusion imaging

Objective: Sentinel node biopsy (SNB) is indicated for axillary lymph nodemetastasis-negative cases (N0), but clarification of the indicationmay increase treatment efficiency. Fluorine-18-labeled 2-fluoro-2-deoxy-D-glucosepositron emission tomography (FDG-PET) may have a high positivepredictive value in diagnosis of axillary lymph node metastasis. Methods: Ninety-two breasts/axillae were analyzed retrospectively in90 patients (median age 54.6-year old, median primary tumor1.7 cm). FDG-PET/computed tomography was used to indicate SNBin N0 cases. Axillary lymph node dissection (ALND) was performedin cases that were axillary lymph node metastasis-positive (PETN+) on FDG-PET/CT. Results: Seventy-four (80.4%) and 18 (19.6%) of the 92 axillae were diagnosedas metastasis-negative (PET N0) and PET N+, respectively, byFDG-PET/CT. SNB was performed in 51 of the 74 PET N0 axillae.ALND was performed in 23 PET N0 axillae (at the patients’request) and in all 18 PET N+ axillae. Of the 74 PET N0 axillae,14 were metastasis-positive (pN+) and 60 were pN0 pathologically,and of the 18 PET N+ axillae, 13 were pN+ and five were pN0.The sensitivity and specificity of FDG-PET/CT for diagnosisof axillary metastasis were 48.1 and 92.3%, respectively, andthe positive and negative predictive values were 72.2 and 81.1%,respectively. Conclusion: The positive detection rate on FDG-PET/CT was insufficient fordetermining an indication of SNB. However, use of an appropriatecut-off for SUV_max (the positive rate was 90.9% with a cut-offof 2.0) and exclusion of surgically biopsied cases may achievea clinically applicable positive detection rate.