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

OBJECTIVE

Epithelial ovarian cancer (EOC) spreads intra-abdominally and to the retroperitoneal lymph nodes. A greater number of distant metastases are revealed by (18)F-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.

METHODS

Thirty 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.

RESULTS

In 20/30 patients (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.

CONCLUSIONS

A 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.