(18)F-FDG/(18)F-FES standardized uptake value ratio determined using PET predicts prognosis in uterine sarcoma

We investigated whether 16α-[(18)F]-fluoro-17β-estradiol ((18)F-FES) and (18)F-fluoro-deoxyglucose (FDG) uptake measured using positron emission tomography (PET) predicted prognosis in 18 patients with different histological subtypes of uterine sarcoma. Standardized uptake values (SUVs) and (18)F-FDG/(18)F-FES SUV ratios were determined, and their correlations with progression-free (PFS) and overall survival (OS) were examined. Ten patients died from local recurrence or metastasis, and one more experienced recurrence, during the at least 36-month follow-up period. Patients with higher (18)F-FDG SUVs (> 5.5) had worse OS (p = 0.007) and tended toward worse PFS (p = 0.11), while patients with lower 18F-FES SUVs (≤ 1.5) had worse PFS (p = 0.03) and tended toward worse OS (p = 0.19). Patients with (18)F-FDG/(18)F-FES ratios > 2.6 had worse PFS (p = 0.009) and OS (p = 0.005). The 5-year PFS and OS rates were 75% and 88% for patients with lower ratios, but were only 10% and 20% for those with higher ratios. These results suggest that pretreatment tumor (18)F-FDG/(18)F-FES ratio is useful for predicting the prognosis of uterine sarcoma patients.