The Role of Axillary SUVin F-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.

Key Words: Breast cancer, Positron emission tomography, SUVmax values, Axillary lymph node, ACOSOG Z0011.