Overall survival and progression-free survival in patients with primary brain tumors after treatment: is the outcome of [18F] FDOPA PET a prognostic factor in these patients?

Aim: To investigate the progression-free survival (PFS) and the overall survival (OS) in a population affected by primary brain tumors (PBT) evaluated by [18F]-l-dihydroxyphenylalanine ([18F] FDOPA) positron emission tomography/computed tomography (PET/CT). Materials and methods: 133 subjects with PBT (65 women and 68 men, mean age 45 ± 10 years old) underwent 18F FDOPA PET/CT after treatment. Of them, 68 (51.2%) were Grade II, 34 (25.5%) were Grade III and 31 (23.3%) were Grade IV. PET/CT was scored as positive or negative and standardized uptake value ratio (SUVr) was calculated as the ratio between SUVmax of the lesion vs. that of the background. Patients have been observed for a mean of 24 months. Results: The outcome of [18F] FDOPA PET/CT scan was significantly related to the OS and PFS in Grade II gliomas. In Grade II PBT, the OS proportions at 24 months were 100% in subjects with a negative PET/CT scan and 82% in those with a positive scan. Gehan–Breslow–Wilcoxon test showed a significant difference in the OS curves (P = 0.03) and the hazard-ratio was equal to 5.1 (95% CI of ratio 1.1–23.88). As for PFS, the proportion at 24 months was 90% in subjects with a negative PET/CT scan and 58% in those with a positive scan. Gehan–Breslow–Wilcoxon test showed a significant difference in the OS curves (P = 0.007) and the hazard-ratio was equal to 4.1 (95% CI of ratio 1.3–8). We did not find any significant relationship between PET outcome and OS and PFS in Grade III and IV PBT. Conclusions: A positive [18F] FDOPA PET/CT scan is related to a poor OS and PFS in subjects with low-grade PBT. This imaging modality could be considered as a prognostic factor in these subjects.