Purpose: To assess the relationship between F-18-fluoro-ethyl-tyrosine positron emission tomography (FET-PET) parameters of relapsing oligodendroglioma and progression-free survival.
Material and methods: The relationship of clinical parameters, FET-PET parameters (SUVmax, TBRmax, BTV, time-activity curves) and progression-free survival was analyzed using univariate and multivariate analysis in 42 adult patients with relapsing oligodendroglioma. Kaplan-Meier analysis was used to assess survival.
Results: Patients who did not undergo surgical resection of their relapsing tumor had significantly lower PFS if the tumor exhibited an SUVmax above 3.40 than those with an SUVmax below 3.40 (13.1 ± 2.3 months vs. 47.3 ± 6.0 months, respectively, p < .001). Patients who underwent surgery had similar PFS as the aforementioned non-operated patients with low SUVmax (53.6 ± 6.7 months, p = .948). The same was true for TBRmax using a threshold of 3.03 (PFS 12.5 ± 2.4 months vs. 44.0 ± 6.3 months / 53.6 ± 6.7 months, respectively; p < .001 / p = .825). Also, subjects with BTV below 10 cm3 that did not undergo surgery had a similar PFS as subjects who underwent surgery (40.2 ± 6.0 months vs. 52.4 ± 8.9 months, respectively, p = .587). Subjects with BTV above 10 cm3 and without surgery had a significantly worse PFS (13.8 ± 3.3 months, p < .001). Multivariate analysis showed that the prognostication by clinical parameters is improved by adding TBRmax to the model (AUC 0.945 (95% CI: 0.881-1.000), true classification rate 88.1%).
Conclusion: FET-PET may provide added value for the prognostication of relapsing oligodendroglioma in addition to clinical parameters.