Prediction of Axillary Nodal Status according to the Axillary Lymph Node to Primary Breast Tumor Maximum Standardized Uptake Value Ratio on 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

ABSTRACT

PURPOSE: This study aimed to evaluate the usefulness of the axillary lymph node to primary breast tumor maximum standardized uptake value (SUVmax) ratio in 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for predicting the presence of metastasis in axillary lymph nodes. METHODS: Herein, 196 consecutive patients with breast cancer who underwent PET/CT before surgery from January 2009 to January 2013 were included. We calculated the axillary lymph node to primary breast tumor SUVmax ratio using PET/CT. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the ratio were compared with those of nodal SUVmax and axillary ultrasonography. Axillary node metastasis was confirmed with sentinel node biopsy or axillary dissection. RESULTS: The SUVmax ratio (cutoff, 0.14; area under the curve, 0.741) had 55.4% sensitivity, 91.6% specificity, 76.6% PPV, and 80.5% NPV for predicting axillary node metastasis. No significant difference was observed in terms of predicting axillary node metastasis among the SUVmax ratio, nodal SUVmax, and ultrasonography. In the multivariate analysis, primary tumor size (p=0.014), SUVmax of the primary tumor (p=0.011), axillary ultrasonography findings, nodal SUVmax, and SUVmax ratio were significantly associated with lymph node metastasis (p<0.001). CONCLUSION: The axillary lymph node to primary breast tumor SUVmax ratio predicted axillary lymph node metastasis, although no significant difference in diagnostic performance was observed between PET/CT and ultrasonography. The axillary lymph node to primary breast tumor SUVmax ratio may be considered an additional method for the preoperative evaluation of axillary lymph node status.