Staging of High-Risk Endometrial Cancer With PET/CT and Sentinel Lymph Node Mapping

PURPOSE: The aim of this study was to evaluate the role of PET/CT and sentinel lymph node (SLN) biopsy in staging high-risk endometrial cancer patients (G2 and deep myometrial invasion, G3, serous clear cell carcinoma or carcinosarcoma) in early clinical stage. PATIENTS AND METHODS: From January 2006 to December 2012, high-risk early-stage endometrial cancer patients performing PET/CT scan followed by surgery (systematic pelvic ± aortic lymphadenectomy) were included. From December 2010, SLN mapping with Tc-albumin nanocolloid and blue dye cervical injection was included in our clinical practice and additionally performed. Histological findings were used as the reference standard. RESULTS: Ninety-three patients were included, of which 22 of 93 had both PET/CT and SLN biopsy. The median number of dissected lymph nodes (LNs) was 28. Nineteen women (20.4%) had pelvic LN metastases; 14 were correctly identified by PET/CT. Among 5 false-negative cases, 3 occurred after the introduction of SLN mapping due to detection of micrometastases by ultrastaging. On overall patient-based analysis, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT for pelvic LN metastases were 73.7%, 98.7%, 93.6%, 93.3%, 93.6%, respectively. CONCLUSIONS: PET/CT demonstrated moderate sensitivity and high specificity in detecting pelvic LN metastases; its high positive predictive value (93.3%) is useful to refer patients to appropriate debulking surgery. Sentinel LN mapping and histological ultrastaging increased the identification of metastases (incidence, 18.3%-27.3%) not detectable by PET/CT because of its spatial resolution. The combination of both modalities is promising for nodal staging purpose.