Lymph node metastasis in patients with clinical early-stage cervical cancer: detection with integrated FDG PET/CT

Abstract

Purpose: To prospectively determine the accuracy of combination positron emission tomography-computed tomography (PET/CT) in lymph node staging in patients with early-stage cervical cancer, with histopathologic results as the reference standard.

Materials and methods: The study was institutional review board approved, and all patients gave informed consent. Forty-seven consecutive women aged 29-71 years with clinical stage IA or IB cervical carcinoma were included in the study. All 47 patients were scheduled for radical hysterectomy with pelvic lymph node dissection. Before surgery, all patients underwent fluorine 18 fluorodeoxyglucose (FDG) PET/CT. PET/CT findings were interpreted by two readers in consensus and then compared with histopathologic results. At histopathologic examination, the dissected lymph nodes were classified as nonmetastatic or metastatic.

Results: Fifteen (32%) patients had metastatic lymph nodes at histopathologic examination, and 32 (68%) had no histopathologically confirmed nodal metastasis. Of the total 1081 lymph nodes histopathologically sampled, 18 were found to be positive for malignant cells. The overall node-based sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 72% (13 of 18), 99.7% (1060 of 1063), 81% (13 of 16), 99.5% (1060 of 1065), and 99.3% (1073 of 1081), respectively. Corresponding values for PET/CT-based diagnosis of lymph nodes larger than 0.5 cm in diameter were 100% (13 of 13), 99.6% (675 of 678), 81% (13 of 16), 100% (675 of 675), and 99.6% (688 of 691), respectively. The overall patient-based sensitivity, specificity, PPV, NPV, and accuracy of PET/CT were 73% (11 of 15), 97% (31 of 32), 92% (11 of 12), 89% (31 of 35), and 89% (42 of 47), respectively.

Conclusion: PET/CT proved to be valuable for lymph node staging in patients with early-stage cervical cancer, with short-axis diameter greater than 0.5 cm being the size threshold for accurate depiction of metastatic nodes.