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 node metastasis-negative cases (N0), but clarification of the indication may increase treatment efficiency. Fluorine-18-labeled 2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) may have a high positive predictive value in diagnosis of axillary lymph node metastasis. Methods: Ninety-two breasts/axillae were analyzed retrospectively in 90 patients (median age 54.6-year old, median primary tumor 1.7 cm). FDG-PET/computed tomography was used to indicate SNB in N0 cases. Axillary lymph node dissection (ALND) was performed in cases that were axillary lymph node metastasis-positive (PET N+) on FDG-PET/CT. Results: Seventy-four (80.4%) and 18 (19.6%) of the 92 axillae were diagnosed as metastasis-negative (PET N0) and PET N+, respectively, by FDG-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 diagnosis of axillary metastasis were 48.1 and 92.3%, respectively, and the positive and negative predictive values were 72.2 and 81.1%, respectively. Conclusion: The positive detection rate on FDG-PET/CT was insufficient for determining an indication of SNB. However, use of an appropriate cut-off for SUV_max (the positive rate was 90.95 with a cut-off of 2.0) and exclusion of surgically biopsied cases may achieve a clinically applicable positive detection rate.