Preoperative risk stratification using (18)F-FDG PET/CT in women with endometrial cancer

The aim of this study is to evaluate the usefulness of (18)F-FDG PET/CT for preoperative stratification of high-risk and low-risk carcinomas in patients with endometrial cancer.

60 women (mean age 53.8±9.9 years) with endometrial cancer, who underwent (18)F-FDG PET/CT for preoperative staging work-up, followed by primary cytoreductive surgery, were enrolled in this study. Maximum and mean standardized uptake values (SUVmax, SUVmean) of endometrial tumors were measured, and compared with the various clinicopathologic findings obtained after surgery. Tumour aggressiveness was classified as high-risk and low-risk carcinomas. Patients with stage I or II, endometrioid adenocarcinoma, histologic grade 1 or 2, invasion of less than half of the myometrium, maximum tumor size less than 2.0 cm, and absence of cervical invasion and lymphovascular space involvement (LVSI) were classified as the low-risk carcinoma group. The remaining patients were classified as the high-risk carcinoma group.

In univariate analysis, SUVmax of the primary endometrial tumor was significantly higher in patients who were in a postmenopausal state (p=0.047), large (>2 cm) primary tumor (p<0.001), nonendometrioid subtype (p=0.024), invasion of more than half of the myometrium (p=0.020), or LVSI (p=0.004). SUVmax differed significantly according to FIGO stage (p=0.013) and histologic grade (p<0.001). In multivariate analysis, FIGO stage, histologic grade, LVSI, and maximum tumor size demonstrated a significant association with SUVmax (p<0.001; r=0.843, r(2)=0.711). SUVmean showed similar results. Forty-one (68.3%) patients were diagnosed postoperatively as high-risk and 19 patients (31.7%) as low-risk carcinoma. Patients with high-risk carcinoma (12.1±6.1) showed significantly higher SUVmax than patients with low-risk carcinoma (5.8±2.8, p<0.001). The optimal SUVmax cut-off value of 8.7, determined by ROC analysis, revealed 75.6% sensitivity, 89.5% specificity, and 81.7% accuracy for risk stratification.

High-risk endometrial cancer might be differentiated by means of higher SUVmax from low-risk endometrial cancer. (18)F-FDG FDG PET/CT can be applied preoperatively for stratification of risk in patients with endometrial cancer.