1. Department of Nuclear Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
2. Department of Ultrasound, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
*These authors contributed equally to this work.
Purpose: To evaluate the value of 18F-FDG positron emission tomography (PET)/computed tomography (CT) for determining the presence of residual tumors after curettage in patients with endometrial cancer.
Methods: Preoperative 18F-FDG PET/CT was performed in 90 women with endometrial cancer. PET/CT parameters and clinical characteristics were compared between patients with and without residual tumors. The clinical characteristics of patients with residual tumors that showed low 18F-FDG uptake were also analyzed.
Results: Among the 90 patients, 86 had residual tumors. ROC analysis identified a lesion SUVmax value of 5.0 as the optimal cut-off value for predicting whether or not patients had a residual tumor. With the SUVmax cut-off of 5, the sensitivity, specificity, positive predictive value, and negative predictive values for residual tumor prediction were 87.2%, 100%, 100%, and 26.7%, respectively. Univariate analysis showed significant associations between the high PET group (SUVmax > 5) and low PET group (SUVmax ≤ 5), and histologic type (P = 0.043) and tumor size (P < 0.001) in patients with residual tumors. In patients with low-grade and clear cell carcinomas and a tumor size < 1.35 cm, the probability of being in the low-PET group was 47.6%. In such patients, major parts of the residual tumors showed low 18F-FDG uptake, similar to that in patients with no residual tumors.
Conclusion: SUVmax was the lone predictive value for the presence of residual tumors after curettage in patients with endometrial cancer. Lesion SUVmax greater than 5 suggested a high possibility of residual tumors. In patients with low-grade and clear cell carcinomas with tumor size < 1.35 cm, residual tumors may present low 18F-FDG uptake, mimicking the metabolic phenotypes of patients without residual tumors.
Keywords: PET/CT, endometrial cancer, SUVmax, residual tumor