The Role of FDG PET/CT to Evaluation of Axillary Lymph Nodes after Neoadjuvant Chemotherapy in Breast Cancer

To determine the diagnostic value of breast and axillary maximum standard uptake (SUVmax) values for predicting ypT0 and ypN0 separately.

A descriptive study.

Department of Medical Oncology, Haydarpasa Numune Training and Research Hospital, between May 2017 and September 2020.  Methodology: Consecutive patients with operated breast cancer (BC) after neoadjuvant chemotherapy (NAC) were evaluated. SUVmax on FDG-PET/CT after NAC at both primary tumour (postSUVmax-T) and axillary lymph nodes (postSUVmax-N) were assessed to predict the ypT0 and the ypN0, respectively.  Results: Clinically meaningful correlation was detected between postSUVmax-N with ypN0 in patients with human epidermal receptor-positive (Her2+) and triple-negative (TN) BC (in Her2+ BC: r=0.596, p <0.001, in TN BC: r=0.782, p = 0.001). The postSUVmax-N predicted ypN0 with 90.5% positive predictive value (PPV) and 85.7% negative predictive value (NPV) in patients with Her2+ and TN BC. The postSUVmax-T predicted ypT0 with 87.5% PPV and 100% NPV in patients with TN BC (AUC: 0.938, P <0.01) Conclusion: According to this study's findings, the FDG-PET/CT may be an alternative to sentinel lymph node biopsy (SNB) to protect patients from axillary lymph node dissection when the expected FNR of the SNB is high in patients with Her+ and TN BC. Key Words: Breast cancer, FDG PET/CT, Neoadjuvant therapy.