Total of 27 patients with GBM progression on the structural MRI were retrospectively included into this study. The basic characteristics of the study sample are summarized in Table 1.
The study sample was divided into two subgroups of early (less then 4 months) and late (over 4 months) recurrence.
Thirteen patients presented with early relapse within 4 months after the end of IMRT; fourteen patients developed late recurrence (5 – 72 months).
The independent-samples Mann-Whitney U test (Table 3) showed significant (p value 0.000) difference between the two study subgroups in Lip+Lac ppm,
NAA ppm,
Cr ppm levels and Cho/Cr,
NAA/Cr,
Lip + Lac/Cr ratios; moderate (p value 0,041) difference in ADCmean values.
Logistic regression analysis was performed on all variables presented in Table 3.
The Omnibus Model Test significance p < 0.000.
The Hosmer–Lemeshow test for goodness of fit showed increase of predictive value of logistic regression model from 51.9% to 100%.
Discriminatory power of the parameters to predict early relapse was assessed by receiver operating characteristic (ROC) curve analysis and the calculated areas under curve (AUC) and the corresponding p values.
The ROC analysis established cut-off values to predict early recurrence presented in Table 2.
Fig. 9: Graph 1. Receiver operating characteristic (ROC) curve analysis and the calculated areas under curve (AUC).
The GTV and transcallosal spread showed only moderate correlation with time to relapse (p value < 0,05).
In the present study,
the concentrations of Lip + Lac,
NAA,
Cr and Cho/Cr,
NAA/Cr and LL/Cr ratios were significantly higher in the subgroup of patients with early GBM relapse.
Fig. 10: Graph 2. Box plots of the peaks and ratios of the metabolites in the patients with cerebral GBM at presentation. The horizontal thick line is the median, the upper and lower ends of the boxes are the 3rd and 1st quartiles, and the vertical lines show the full range of values in the data.
High levels of choline (Cho) are often observed in areas with high cellular membrane turnover.
N-acetyl aspartate (NAA) is another metabolite found in neurons,
and creatine (Cr) is rich in regions active with energy metabolism.
A scoring system using these parameters may potentially increase the accuracy of detecting patients with poor response (non-responders) to a standard first line treatment and shift their management towards more aggressive salvage treatment.