FDG PET/CT in staging of advanced epithelial ovarian cancer: Frequency of supradiaphragmatic lymph node metastasis challenges the traditional pattern of disease spread

Abstract

ObjectiveEpithelial ovarian cancer (EOC) spreads intra-abdominally and to the retroperitoneal lymph nodes. A greater number of distant metastases are revealed by 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) compared to conventional imaging methods. We aimed to investigate the presence and anatomic distribution of supradiaphragmatic lymph node metastasis (LNM) detected with pretreatment FDG PET/CT. MethodsThirty women with advanced stage (IIC-IV) EOC were scanned with whole body contrast-enhanced FDG PET/CT prior to surgery/neoadjuvant chemotherapy. We performed PET/CT analysis qualitatively and quantitatively. Additionally, contrast-enhanced CT was analyzed blinded to PET/CT scan. Intra-abdominal dissemination was verified by surgery and histopathology. Metabolically active lymph nodes were biopsied when possible. The clinical characteristics of patients with and without supradiaphragmatic LNM were compared. ResultsIn 20/30patients (67%) FDG PET/CT detected supradiaphragmatic LNM in one or more locations, whereas conventional CT found LNM in 10 patients (33%). Fourteen patients had parasternal, 14 cardiophrenic, 8 other mediastinal, 6 axillar, and 1 subclavian LNM. Microscopy of all four biopsied lymph nodes (three axillar and one subclavian) confirmed metastatic dissemination. The patients with supradiaphragmatic LNM had significantly more ascites (p<0.01), higher CA 125 levels, and more frequent subdiaphragmal carcinomatosis (p<0.03) compared to patients without supradiaphragmatic LNM in preoperative FDG PET/CT. ConclusionsA significant number of patients with advanced EOC showed supradiaphragmatic LNM in pre-treatment PET/CT. Our findings suggest that the route of EOC cells from the peritoneal cavity to the lymphatic system permeates the diaphragm mainly to the cardiophrenic and continues to parasternal lymph nodes.