Objective: The objective of our study was to evaluate the accuracy of integrated PET and CT (PET/CT) using (18)F-FDG in detecting pelvic and paraaortic lymph node metastasis in patients with endometrial cancer, using surgical and histopathologic findings as the reference standard.
Subjects and methods: Forty patients with clinical stages IA to IIIC underwent radical hysterectomy, including pelvic lymphadenectomy with or without paraaortic lymphadenectomy, after FDG PET/CT. Lymphadenectomy involved removing all visible lymph nodes in the surgical fields. PET/CT findings were interpreted by two experienced radiologists in consensus and compared with histopathologic results. The criterion for malignancy on PET/CT images was increased radiotracer uptake by a lymph node independent of node size.
Results: In total, 62 pathologically positive nodes were found in 10 patients and 60 of 62 dissected metastatic nodes were identified on the CT component. The overall node-based sensitivity, specificity, and accuracy of PET/CT for detecting nodal metastases were 53.3% (32/60), 99.6% (1,419/1,424), and 97.8% (1,451/1,484), respectively. The sensitivity for detecting metastatic lesions 4 mm or less in diameter was 16.7% (4/24), that for lesions between 5 and 9 mm was 66.7% (14/21), and that for lesions 10 mm or larger was 93.3% (14/15). The overall patient-based sensitivity, specificity, and accuracy were 50% (5/10), 86.7% (26/30), and 77.5% (31/40), respectively.
Conclusion: Integrated FDG PET/CT is superior to conventional imaging techniques, but it is only moderately sensitive in predicting lymph node metastasis preoperatively in patients with endometrial cancer. Even PET/CT should not replace lymphadenectomy.