The Relation Between Tumor and Axillary Lymph Node SUV Values with the Presence of Distant Metastases in Staging F18 FDG PET/CT in Breast Cancer

Introduction: We aimed to investigate the relation between primary tumor and axillary lymph node maximum standardized uptake values (SUVmax) with the presence of distant metastases at initial staging of breast cancer. Materials and Methods: Fifty-seven women who were referred to our clinic for staging positron emission tomography/computed tomography (PET/CT) with diagnosis of breast cancer were included in the study. Immunohistochemical (IHC) features of the primary tumor [hormone receptor (HR), human epidermal growth factor receptor type-2 (HER2), Ki67 index] were reviewed retrospectively. All patients’ HR status was positive and HER2 status was negative. Primary tumor SUVmax (Tmax) and axillary lymph node SUVmax (Nmax) values and primary tumor-to-axillary lymph node (T/N) ratios were calculated in PET/CT. Patients were divided into two groups as metastatic and non-metastatic according to PET/CT findings. The differences between groups in terms of age, Ki67 index and SUV values were statistically analyzed. Results: The mean age of the patients was 52±14.4 (range 25-79 years). According to PET/CT findings, the patients were divided in two groups, 57% metastatic (n = 33) and 43% non-metastatic (n = 24). While no statistically significant difference was observed between the two groups in terms of age, Ki67 index and Tmax averages, statistically significant differences were found between Nmax values (p <0.001) and T/N ratios (p=0.001). Cut-off value in association with distant metastasis was 7,8 for Nmax value and 8,5 for T/N ratio on ROC curve analysis. Discussion: Accurate staging is important in terms of treatment plan and prediction of disease prognosis in breast cancer. In our study, it was thought that the difference in Nmax values and T/N ratios, independent of Tmax values, could be a determinant in terms of the overlooked and possible early metastatic disease indicator in the patient group without known distant metastasis.