Different Prognostic Implications of 18F-FDG PET Between Histological Subtypes in Patients With Cervical Cancer

This study aimed to investigate whether the predictive values of intensity- and volume-based PET parameters are different between histological subtypes in patients with cervical cancer. Ninety patients, 65 with squamous cell carcinoma (SCC) and 25 with non-SCC (NSCC), who underwent pretreatment ¹⁸F-FDG PET/CT and pelvic MRI, were studied retrospectively. In addition to SUVmax and SUVmean, metabolic-tumor-volume (MTV) was determined by thresholding of 40% SUVmax and total-lesion-glycolysis (TLG) was calculated. Clinical factors and PET metabolic indices were compared between SCC and NSCC. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method with cut-offs determined by ROC analyses to stratify SCC and NSCC patients separately. Factors associated with survival were assessed with univariate and multivariate analyses using the Cox regression model. No significant differences were observed in clinical factors other than tumor size or ¹⁸F-FDG PET metabolic indices between SCC and NSCC. The Kaplan-Meier estimates of 2-year PFS and OS rates were 60% and 70% for SCC and 40% and 76% for NSCC, respectively. Multivariate analyses showed that MTV and TLG were the independent prognostic factors for PFS and OS in SCC; in contrast, SUVmax was the independent prognostic factor for PFS and OS in NSCC. Metabolic burden (MTV and TLG) could be beneficial for the prognostic prediction of cervical SCC patients; in contrast, metabolic intensity (SUVmax) could be beneficial for the prognostic prediction of NSCC patients. The different prognostic implications might be based on the differences of tissue integrity and histological heterogeneity between SCC and NSCC.