[18F]FDG-PET/CT metabolic parameters as useful prognostic factors in cervical cancer patients treated with chemo-radiotherapy

Abstract

Background: To compare the prognostic value of different anatomical and functional metabolic parameters determined using [18F]FDG-PET/CT with other clinical and pathological prognostic parameters in cervical cancer (CC). Methods: Thirty-eight patients treated with standard curative doses of chemo-radiotherapy (CRT) underwent pre- and post-therapy [18F]FDG-PET/CT. [18F]FDG-PET/CT parameters including mean tumor standardized uptake values (SUV), metabolic tumor volume (MTV) and tumor glycolytic volume (TGV) were measured before the start of CRT. The post-treatment tumor metabolic response was evaluated. These parameters were compared to other clinical prognostic factors. Survival curves were estimated by using the Kaplan-Meier method. Cox regression analysis was performed to determine the independent contribution of each prognostic factor. Results: After 37months of median follow-up (range, 12-106), overall survival (OS) was 71% [95% confidence interval (CI), 54-88], disease-free survival (DFS) 61% [95% CI, 44-78] and loco-regional control (LRC) 76% [95% CI, 62-90]. In univariate analyses the [18F]FDG-PET/CT parameters unfavorably influencing OS, DFS and LRC were pre-treatment TGV-cutoff ≥562 (37 vs. 76%, p = 0.01; 33 vs. 70%, p = 0.002; and 55 vs. 83%, p = 0.005, respectively), mean pre-treatment tumor SUV cutoff ≥5 (57 vs. 86%, p = 0.03; 36 vs. 88%, p = 0.004; 65 vs. 88%, p = 0.04, respectively) and a partial tumor metabolic response after treatment (9 vs. 29%, p = 0.0008; 0 vs. 83%, p < 0.0001; 22 vs. 96%, p < 0.0001, respectively). After multivariate analyses a partial tumor metabolic response after treatment remained as an independent prognostic factor unfavorably influencing DFS and LRC (RR 1:7.7, p < 0.0001, and RR 1:22.6, p = 0.0003, respectively) while the pre-treatment TGV-cutoff ≥562 negatively influenced OS and DFS (RR 1:2, p = 0.03, and RR 1:2.75, p = 0.05). Conclusions: Parameters capturing the pre-treatment glycolytic volume and metabolic activity of [18F]FDG-positive disease provide important prognostic information in patients with CC treated with CRT. The post-therapy [18F]FDG-PET/CT uptake (partial tumor metabolic response) is predictive of disease outcome.