The Role of Axillary SUVmax in 18F-FDG PET/CT in Predicting the Number of Axillary Metastases of Breast Cancer

Objective: To investigate the role of positron emission tomography/computed tomography (PET-CT) in determining the maximum number of axillary lymph node metastasis (ALNM) detectable in sentinel lymph node biopsy (SLNB).Study Design: Observational study.Place and Duration of the Study: Sivas Cumhuriyet University Faculty of Medicine, Turkiye, from January 2015 to August 2021.Methodology: A total of 104 breast cancer patients who underwent surgery after a PET-CT scan were examined. A receiver operating characteristic (ROC) analysis was utilised to determine optimal cut-off values for the standardised uptake values of the primary tumour (pSUVmax) and axillary lymph nodes (nSUVmax) in the presence of ALNM and the presence of more than two ALNMs.Results: The presence of more than two ALNMs was associated with pSUVmax, nSUVmax, LVI, and the number of LNs detected on PET-CT. In the ROC analysis, for the ability to predict more than two ALNMs in SLNB/axillary lymph node dissection (ALND), cut-offvalues were calculated as 4.65 for pSUVmax (AUC=0.669, sensitivity=66.7%, specificity=62%, PPV=0.482, NPV=0.800, p=0.006) and 1.75 for nSUVmax (AUC=0.838, sensitivity=81.8%, specificity=88.7%, PPV= 0.676, NPV=0.913, p<0.001).Conclusion: Low sensitivity, NPV, and accuracy values that limit the use of PET-CT in preoperative axillary evaluation can be increased by targeting the criterion of more than two ALNMs. Thus, PET-CT can be used more effectively in axilla management.