Relationship Between Staging FDG PET/CT Findings and Distribution of Metastatic Sites in Metastatic Breast Cancer

Introduction: We aimed to investigate the relationship between staging FGD PET/CT findings and metastasis distribution and histopathological features of primary tumor in patients with metastatic breast cancer at diagnosis time. Materials and Methods: Eighty patients with breast cancer who underwent F-18 FDG PET/CT for staging were included. The patients with newly diagnosed metastatic disease were included. Age and histopathological features of the primary tumor were recorded. The distant metastases sites, the numbers of metastasis and metastatic axillary/non-axillary lymph nodes were reviewed from PET/CT. The maximum standardized uptake(SUVmax) values were measured. Results: All patients(n:80,mean age 58.0±14.4) had invasive breast carcinoma. Age was significantly related to the presence of lung metastases(p=0.006, mean ages 54y vs 64y).Only liver metastasis had a significant relationship with primary tumor SUVmax values and tumor molecular profile. The patients with HR+/HER2-(7/60 patients, 11.7%) had relatively less liver metastasis than with the other subtypes (9/20patients, 45%). There were significant associations between SUVmax of axillary lymph node(p=0.02), primary tumor(p=0.001), liver metastasis(p=0.02) and tumor subtypes. The numbers of distant metastasis were related with the numbers of axillary lymph node metastasis(p=0.02) and the highest SUVmax of distant metastasis(p=0.001). Discussion: Accurate detection of distant metastases in breast cancer at the time of diagnosis is of great importance in terms of treatment planning and prognosis of the disease. FDG PET/CT is a very reliable modality in determining distant metastasis and their distribution, and as a result of our study, we suggest that PET/CT findings can predict factors with prognostic importance.