Radiol Oncol 2023; 57(2): 201-210. doi: 10.2478/raon-2023-0009 201 research article Cognitive functioning in a cohort of high-grade glioma patients Andreja Cirila Skufca Smrdel 1,2 , Anja Podlesek 2 , Marija Skoblar Vidmar 3,4 , Jana Markovic 1 , Jana Jereb 1 , Manja Kuzma Okorn 5 , Uros Smrdel 3,4 1 Department of Psycho-Oncology, Institute of Oncology Ljubljana, Ljubljana, Slovenia 2 Department of Psychology, Faculty of Arts, University of Ljubljana, Slovenia 3 Division of Radiotherapy, Institute of Oncology Ljubljana, Ljubljana, Slovenia 4 Faculty of Medicine, University of Ljubljana, Slovenia 5 University Medical Centre Ljubljana, Slovenia Radiol Oncol 2023; 57(2): 201-210. Received 29 November 2022 Accepted 31 December 2022 Correspondence to: Assist. Prof. Uroš Smrdel, M.D., Ph.D., Division of Radiotherapy, Institute of Oncology Ljubljana, Zaloška 2, SI-1000 Ljubljana, Slovenia. E-mail: usmrdel@onko-i.si Disclosure: No potential conflicts of interest were disclosed. This is an open access article distributed under the terms of the CC-BY li-cense (https://creativecommons.org/licenses/by/4.0/). Background. High grade gliomas are associated with cognitive problems. The aim of the study was to investigate cognitive functioning in a cohort of patients with high grade glioma, according to isocitrate dehydrogenase (IDH) and methyl guanine methyl transferase (MGMT) status and other clinical characteristics. Patients and methods. The patients with the high-grade glioma treated in Slovenia in given period of time were included in study. Postoperatively they completed neuropsychological assessment consisting of Slovenian Verbal Learning Test, Slovenian Controlled Oral Word Association Test, Trail Making Test Part A and B and self-evaluation questionnaire. We analysed results (z-scores and dichotomized results) also according to IDH mutation and MGMT methylation. We examined differences between groups using T-test, Mann-Whitney U, χ2 and Kendall’s Tau tests. Results. Out of 275 patients in the cohort, we included 90. Forty-six percent of patients were unable to participate due to poor performance status and other conditions related to tumour. Patients with the IDH mutation were younger, with better performance status, larger proportions of grade III tumours and MGMT methylation. In this group cognitive functioning is significantly better in the domains of immediate recall, short delayed recall and delayed recall, and in the fields of executive functioning and recognition. There were no differences in cognitive functioning in regard to MGMT status. Grade III tumours were associated with more frequent MGMT methylation. Self-assessment proved week tool, associated only with immediate recall. Conclusions. We found no differences in cognitive functioning according to MGMT status, but cognition was better when IDH mutation was present. In a cohort study of patients with high-grade glioma, almost half were unable to par- ticipate in a study, which points to an overrepresentation of patients with better cognitive functioning in the research. Key words: cognition; high grade glioma; IDH1 mutation; MGMT methylation Introduction Malignant gliomas are group of aggressive brain tumours, comprising anaplastic astrocytoma (Grade III), anaplastic oligodendrogliomas (Grade III), anaplastic astrocytoma (Grade IV) and glio- blastomas (Grade IV). 1 Anaplastic gliomas are still some of the most challenging tumours for patient and caregivers, but also for the therapist. Although there are some cautious advances in this field, there is still a grim outlook for the patients. As a number of patients is ill responding to treatment there are efforts for identifying those who respond well and those who would benefit from a change in treatment strategy. Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 202 Genetic and epigenetic markers like isocitrate dehydrogenase (IDH) mutations, loss of heterozy- gosity of 1p/19q(LoH 1p/19q), and methyl guanine methyl transferase (MGMT) promoter methylation have recently helped to stratify patients, removing the mixed histology like anaplastic oligoastrocy- toma and introducing Grade IV astrocytoma. In IDH1 mutated patients’ survival was markedly longer, as is in anaplastic oligodendrogliomas (with LoH 1p/19q). Prior to widespread genetic testing, it was already clear that patients harbour- ing methylation of MGMT gene promoter fare bet- ter comparing to those without. 2-4 Brain tumours are also associated with im- paired cognitive functioning, due to tumour alone but also due to treatment. Cognitive impairment can manifest already at the time of diagnosis; the prevalence of cognitive deficits varies from 60 to 85% in different studies. 5 The most common are in the fields of verbal memory, executive function- ing, psycho-motor speed, but also attention and language. 6-9 Cognitive functioning is also one of the prog- nostic factors for survival. Early findings suggest- ed that cognitive decline is preceding radiologi- cal progression, which was not confirmed by all studies. 10-12 Further studies confirmed cognitive impairment as independent prognostic factor in newly diagnosed patients, both at baseline and in the period after surgery. 13-16 It was shown that IDH1 mutation (IDH1-mut) is not only an important prognostic factor, but it is also associated with better cognitive functioning. Many studies have shown that cognitive function- ing is better in IDH1-mut patients when compared with IDH1-wildtype (IDH1-wt) patients. 17-19 Among possible causes of the better cognitive functioning of patients with IDH1-mut is brain plasticity which could be affected negatively by the greater tumour growth rate in IDH1-wt tumours, while remaining intact in less invasive IDH1-mut tumours. Preserved cognitive functioning might also be related to the tumour microenvironment, with more pronounced lymphocyte infiltration and programmed death-ligand 1 (PD-L1) expres- sion in IDH1-wt tumours, or even to differences at the synaptic level. 20 The effect and possible role of the MGMT meth- ylation status in patients’ cognitive functioning is even less clear. Most clinical studies focus on in- vestigating patients with MGMT promoter meth- ylation (MGMT-met), with cognitive function as a secondary outcome. 21 According to one study, the absence of MGMT promoter methylation (MGMT- unmet) predicts greater cognitive deficit when pa- tients are treated with radiochemotherapy. 22 The MGMT-met therefore can be considered a predic- tive marker for development of cognitive impair- ment, but further research about its role in cogni- tive functioning as well as the prognosis needed. Here the challenge is the frequent overlap of MGMT promoter methylation with the IDH1 mu- tation, which, in conjunction with relatively small number of patients in the high-grade glioma stud- ies, presents difficulties in statistical analysis. In our study, we examined how the expression of IDH1 mutation and MGMT promoter methyla- tion are linked to the cognitive functioning fol- lowing the operative treatment in the cohort of all Slovene Grade III and Grade IV glioma patients. Patients and methods Patients We analysed the cohort of patients with high grade glioma, treated between March 2019 and December 2021. Their diagnoses (anaplastic astrocytoma, an- aplastic oligodendroglioma or glioblastoma) were histological confirmed. Patients were operated in either of the two neurosurgical departments in Slovenia, then they were referred to Institute of Oncology Ljubljana for evaluation regarding the initiation of radiochemotherapy. At the referral, they consented to be enrolled in the study. Exclusion criteria were histology other than gliomas WHO III/IV , Karnoffsky performance status less than 70% and inability to undergo eval- uation (e.g., marked dysphasia). To be included in the study, they had to be 18 years old or older. The following data were obtained from the medical documentation: age, sex, date of diagno- sis, localization of the tumour, type of surgery, ex- tent of surgery, radiotherapy parameters, systemic therapy, use of corticosteroids, histological, genetic and epigenetic characteristics of tumours. All pa- tients also had a molecular and genetic analysis of the tumour tissue performed, so the IDH1 muta- tions and MGMT promoter methylation status were determined. Cognitive functioning To asses cognitive functioning, we used psycho- metric tests in the domains of verbal memory (Slovenian Verbal Learning Test – TBU, measur- ing immediate recall, short recall, delayed recall and recognition of distracters) 23 , verbal fluency Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 203 (Slovenian Controlled Oral Word Association Test –SCOWA) 24 , psycho-motor speed (Trail Making Test, Part A – TMT A), executive functions (Trail Making Test, Part B – TMT B) 25 , in accordance with the recommendations for use in the studies con- cerning cognitive functioning of cancer patients. 26 The patients also self-evaluated their cognitive functioning on a 0–10 scale (0 = without problems, 10 = extremely intensive problems present). Statistical analysis and ethical consideration We used descriptive statistics with the means val- ues and standard deviation for the demographic data. The correlation between variables was tested with Pearson’s t test or Spearman’s rho test. For each cognitive test, the test scores were analysed either as standardized (z-scores) or as a dichotomized variable: no impairment present (z > –1.5 below the mean of the control group) vs. im- pairment observed (the patient had a z-score lower than –1.5 or was unable to perform the test at all). At the individual level, we analysed the percent- age of impaired patient`s results. We next compared groups of patients with dif- ferent IDH1 statuses and MGMT methylation, using either a t-test or Mann-Whitney U-test (in case that Kolmogorov-Smirnov test of normality showed statistically significant departure from normality) for interval variables, a χ2 test for categorical variables and ordinal variables with Kendall’s Tau test. All hypotheses were tested at a 5-percent alpha error rate. We used the statistical program SPSS, to calcu- late the power of the test we used G*Power 3.1.9.7. Written informed consent was obtained from all the patients before the inclusion in the clinical trial. The study was approved by the Institutional Review Board of the Institute of Oncology Ljubljana and by The National Medical Ethics Committee of the Republic of Slovenia (Approval number 0120- 393/2018/10, date 12/12/2018) and was carried out according to the Declaration of Helsinki. Results Demographics and tumour characteristics At the time the research was performed, 275 pa- tients were diagnosed with glial tumour. Of those, 90 patients were recruited into the study, repre- senting 33% of all patients. Figure 1 shows reasons for patients entering and not entering the study as recorded by oncologists at the time of the first con- sultation. Of the 51% of patients incapable of par- ticipating, in the study the major reason was poor performance status, followed by other tumour and treatment related impairments, representing 46% of ineligible patients, the other common issue was language barrier. Participating patients were 30 to 84-year-old (median [M] = 58.78 years, standard deviation [SD] = 11.31 years). There were more males than females (57 vs. 33). On average, female patients were older (M = 57.67 years, SD = 9.35 years, 39–74 years) than male patients (M = 59.42 years, SD = 12.33 years, 30–84 years), but the age difference was not statis- tically significant (p = 0.481). Of all 90 patients, 78 had Grade IV tumour (all classified as glioblastoma), 8 had anaplastic astro- cytoma, and 4 had anaplastic oligodendroglioma. Fifteen patients had IDH1 mutation (7 anaplastic oligodendroglioma, 4 anaplastic astrocytoma, and 4 glioblastoma). MGMT promoter was methylated in 36 patients (4 anaplastic oligodendroglioma, 5 anaplastic astrocytoma, and 27 glioblastoma), whereas in 1 glioblastoma, 2 anaplastic astrocy- tomas and 1 anaplastic oligodendroglioma we couldn’t determine the methylation status. Patients with Grade III tumours had a statisti- cally better performance status – the Karnoffsky All patients with WHO Grade III and Grade IV gliomas in Slovenia, N = 275 Incapable to enter study (140; 51%) • Poor physical performance (67;24%) • Dysphasia, dysarthria (11; 4%) • Marked cognitive impairment, disoriented (22; 8%) • Treatment related complication (25; 9%) • Language barrier (15; 5%) Eligible patients N =135 (49%) Declined (22; 8%) • Oncological treatment (11; 4%) • To enter study (11; 4%) Unknown (23; 8%) Agreed and participated in the study N = 90 (33%) FIGURE 1. Recruitment protocol, N = 275 Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 204 performance status was 70 in 2 (17%) patients, 80 in 2 (17%) patients, 90 in 8 (67%) patients with Grade III tumours – when compared with patients with Grade IV tumours (in these group, the Karnoffsky performance status was 70 in 30 patients, 80 in 35 patients, 90 in 10 patients, and 100 in 3 patients; U = 251.000, z = -2.75, p = 0.006). Compared to the group of patients with Grade III tumours, the group with Grade IV tumours had a statistically significantly higher percentage of IDH1-mut tumours (73% vs. 5%, χ2(1) = 56.077, p < 0.001, V = 0.789, 1–b = 0.987) and MGMT promoter methylations (60% vs. 36%, χ2(1) = 7.067, p = 0.008, V = 0.280, 1–b = 0.756). Table 2 shows the structure of the sample ac- cording to the expression of IDH1 mutation and MGMT methylation. Five patients had both ge- netic markers expressed, two thirds of patients with IDH1-mut also had MGMT-met expressed, and among patients with expressed methylation, IDH1-mut tumours were present in 27% of pa- TABLE 1. Demographic and medical data Variable Levels f (%) Descriptive statistics Gender Male Female 57 (63%) 33 (37%) Age < 50 years 50–70years > 70 years 17 (19%) 60 (67%) 13 (14%) M = 58.78, SD = 11.31 min = 30, max = 84 Education ≤ 9 years 10–13 years 14–19 years ≥ 20 years 14 (16%) 48 (53%) 26 (29%) 2 (2%) Tumour grade Grade III Grade IV 12 (13%) 78 (87%) Tumour location Frontal Parietal Temporal Occipital central Diffuse 34 (38%) 21 (23%) 26 (29%) 4 (4%) 3 (3%) 2 (2%) Hemisphere Right Left Both 38 (42%) 44 (49%) 8 (9%) Surgery type Biopsy Reduction Gross tumour resection 11 (12%) 49 (54%) 30 (33%) Karnoffsky performance status 70 80 90 100 32 (36%) 37 (41%) 18 (20%) 3 (3%) Corticosteroids (Yes/no, mg) Yes No 66 (73%) 24 (27%) M = 5.55, SD = 4.73 min 0, max 24 Radio-chemotherapy (intention to treat) Yes No 90 (100%) 0 (0%) Time to beginning of adjuvant treatment (in weeks) ≤ 6 weeks ≥ 7 weeks 60 (67%) 30 (33%) M = 5.98, SD = 2.25 min 3, max 15 Epilepsy Yes No 27 (30%) 63 (70%) IDH1 mutation IDH1 mutation IDH1 wild type 15 (17%) 75 (83%) MGMT methylation* Yes No 36 (42%) 50 (58%) IDH1 = isocitrate dehydrogenase 1; M = median; MGMT = methyl guanine methyl transferase; SD = standard deviation Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 205 tients. The difference in the proportion of MGMT methylation in the IDH1-mut and IDH1-wt groups was statistically significant, χ2(1) = 5.333, p = 0.021, V = 0.243, 1–b = 0,82). Cognitive functioning The overview of cognitive evaluation is presented in Table 3. The achievements were impaired (z <–1.5) in a large proportion of the patients, espe- cially in the field of short recall, executive func- tions and psycho-motor speed. The impairment was least frequent in the field of recognition and verbal fluency. The results remained similar, re- gardless of accounting only those who were ca- pable of completing a specific test or the sample as whole – the biggest difference between these two analysis methods is on the TMT A and TMT B tests. We examined on how many out of 7 tests the pa- tients had an impaired test score (z < –1.5 or unable to finish the test) and found that 11 patients (12%) had 0–1 impaired test score, 26 (29%) patients had 2–4 impaired test scores, and 53 (60%) patients had more than 5 impaired test scores. On the 10-point self-evaluation scale of cognitive functioning the mean rating was 3.66, SD = 2.81, min = 0, max = 10; 48 (53%) patients selected rating 0–3, 23 (26%) selected rating 4–6, and 19 (21%) se- lected a rating higher than 7. Correlations between self-assessment and individual tests of cognitive functioning show that self-assessment is weakly but statistically significantly related only to imme- diate recall (r = -0.280, df = 79, t = 2,57, p = 0.012). The cognitive functioning in any of the meas- ured fields was not statistically significantly af- fected by sex, surgery type and the presence or ab- sence of seizures. The test scores did, however, dif- fer with regard to age, education, and performance status. Age was statistically significantly related to participant’s results in the field of verbal fluency (r = -0.278, t = -2.55, df = 79, p = 0.012), immediate recall (r = -0.409, t = -3.96, df = 79, p < 0.001), short delayed recall (r = -0.388, t = 3.72, df = 79, p < 0.001) and de- layed recall (r = -0.333, t = 3.12, df = 79, p = 0.003). Education was significantly related to results in the fields of verbal fluency (r s = 0.381, t = 3.66, df = 79, p < 0.001), immediate recall (r s = 0.334, t = 3.13, df = 79, p = 0.002), short delayed recall (r s = 0.285, t = 2.63, df = 79, p = 0.010), delayed recall (r s = 0.265, t = 2.42, df = 80, p = 0.017) and recognition (r s = 0.264, t = 2.42, df = 79, p = 0.018). Performance status was significantly related to immediate recall (r s = 0.280, t = 2.57 , df = 79, p = 0.012) and delayed recall (r s = 0.296, t = 2.74, df = 79, p = 0.008). We analysed the disease and demographic data and the results of psychological tests with regard to IDH1 mutation. Compared to IDH1-wt patients, patients with tumours harbouring IDH1-mut were statistically significantly younger, had better per- formance status and were more likely to have Grade III tumour and MGMT promoter methyla- tion (Table 4). They functioned better in the field of verbal memory (had a better performance in immediate recall, short delayed recall and delayed recall, measured either with z-scores or as dichot- omised test scores) and in the field of executive TABLE 3. Descriptive statistics for standardized test scores (z–values) and proportion of impaired patients in psychological cognitive functioning tests Domain Test % impaired / all N % impaired / capable Mean z score SD of z scores Visual – motor speed TMT A 68 68 57 2.89 3.57 Executive function TMT B 78 46 59 2.80 2.94 Verbal fluency SCOWA 47 81 41 –1.21 0.88 Memory immediate recall short delayed recall delayed recall recognition SVLT-ir SVLT-sr SVLT-dr SVLT-recog 64 79 63 60 80 60 76 58 52 –1.83 –2.05 –1.92 –2.73 1.11 1.31 1.35 3.36 SCOWA = Slovenian Controlled Oral Word Association Test; SVLT = Shiraz Verbal LearningTest; TMT A = Trail Making Test, Part A; TMT B = Trail Making Test, Part B TABLE 2. Number of patients with different combinations of IDH1 mutation expression and methyl guanine methyl transferase (MGMT) methylation MGMT-met MGMT -unmet Total IDH1-mut 5 10 15 IDH1-wt 49 26 75 Total 54 36 90 I D H 1 - m u t = i s o c i t r a t e d e h y d r o g e n a s e 1 m u t a t i o n ; I D H 1 - w t = i s o c i t r a t e d e h y d r o g e n a s e 1 wildtype; MGMT-met = methyl guanine methyl transferase promoter methylation; MGMT- unmet = methyl guanine methyl transferase absence of promoter methylation Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 206 functioning (measured with dichotomised test scores) (Table 5). Patients with IDH1-mut had on average a sta- tistically significantly lower number of impaired tests results than patients with IDH1-wt (M = 2.93, SD = 2.25vs. M = 4.93, SD = 1.99; U = 286.000, z = -3.04, p = 0.002). 5 (33%) patients with IDH1-mut tu- mours and 6 (8%) patients without IDH1-mut had at most one impaired result on cognitive tests; im- paired results on 2–4 tests had 5 (33%) vs. 21 (28%). Impaired scores on more than 5 tests had 5 (33%) vs. 48 (64%). TABLE 4. Patient characteristics, regarding isocitrate dehydrogenase 1 (IDH1) mutation IDH1-wt (N = 75) IDH1-mut (N=15) Result of the statistical test and effect size Age mean (min/max/SD) 61.50 (31 / 84 / 9.21) 38.75 (30 / 67 / 3.86) t = -5.97, df = 88, p< 0.001 Sex (female / male) 29 / 46 4 / 11 χ2(1) = 0.775, f = -0.93, p = 0.379 Education level (≤ 9 years /10–13 years / 14–19 years / ≥ 20 years) 11 / 40 / 22 / 2 3 / 8 / 4 / 0 τb(3) = -0.06, z = -0.83, p = 0.547 KPS (70/80/90/100) 31 / 34 / 7 / 3 1 / 3 / 11 / 0 τb(3) = 0.403, z = 18.95, p < 0.001 WHO grade (III / IV) 1 /74 11 /4 χ2(1) = 56.08, f = -0.789, p < 0.001 Corticosteroids mg (min/max/SD) 2 (0 / 16 / 6) 5 (0 / 24 / 4.5) t = -1.16, df = 88, p = 0.251 biopsy/reduction/gross tumour resection 9 / 44 / 22 2 / 5 / 8 χ2(2) = 3.65, V = 0.210, p = 0.161 Tumour location (frontal / temporal / parietal / occipital / diffuse / central) 26 / 20 / 21 / 4 / 2 / 2 8 / 1 / 5 / 0 / 1 / 0 NA Hemisphere (right / left / both) 21 / 27 / 6 17 / 17 / 2 χ2(2) = 1.14, V = 0.113, p = 0.566 MGMT (yes / no) 10 / 5 26 /49 χ2(1) = 5.33,f = 0.24, p = 0.021 IDH1-mut = isocitrate dehydrogenase 1 mutation; IDH1-wt = isocitrate dehydrogenase 1 wild type; KPS = Karnoffsky performance status; MGMT = methyl guanine methyl transferase; NA = not available; SD = standard deviation TABLE 5. Cognitive functioning regarding to isocitrate dehydrogenase 1 (IDH1) mutation IDH1–wt IDH-mut Result of the statistical test IDH1–wt IDH1-mut Result of the statistical test N Mean Z score (SD) N Mean Z score (SD) % of impaired % of impaired TMT A 53 3.12 1 (3.84) 15 2.06 (2.23) U = 345.000, z = -0.77, df = 66, p= 0.437 72 46 χ2(1) = 3.67, V = 0.20, p = 0.055 TMT B 33 2.82 1 (3.11) 13 2.76 (2.57) U = 221.500, z = -0.17, df = 66, p = 0.864 82 60 χ 2(1) = 3.87, V = 0.21, p = 0.050 SCOWA 66 -1.28 (0.87) 15 -0.86 (0.84) t = -1.69, df = 79, p = 0.095 51 27 χ2(1) = 2.89, V = 0.18, p = 0.089 SVLT-ir 65 -1.98 (1.06) 15 -1.15 (1.12) t = -2.729, df = 78, p = 0.008 71 33 χ 2(1) = 7.60, V = 0.29, p = 0.006 SVLT-sr 65 -2.20 (1.29) 15 -1.37 (1.22) t = -2.25, df = 78, p = 0.027 84 53 χ2(1) = 7.06, V = 0.28, p = 0.008 SVLT-dr 65 -2.14 (1.27) 15 -0.98 (1.34) t = -3.13, df = 78, p =0.002 69 33 χ2(1) = 6.98, V = 0.28, p = 0.008 SVLT-recog 65 -3.06 1 (3.54) 15 -1.24 (1.91) U = 611.000, z = -2.25, df = 78, p = 0.023 29 26 χ2(1) = 3.00, V = 0.18, p = 0.083 1 the distribution is significantly non-normal IDH1-mut = isocitrate dehydrogenase 1 mutation; IDH1-wt = isocitrate dehydrogenase 1 wildtype;SCOWA = Slovenian Controlled Oral Word Association Test; SD = standard deviation; SVLT = Shiraz Verbal Learning Test; SVLT-dr = SVLT delayed recall; SVLT-ir = SVLT immediate recall; SVLT-recog = SVLT recognition; SVLT-sr = SVLT short delayed recall; TMT A = Trail Making Test, Part A; TMT B = Trail Making Test, Part B Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 207 We found no differences between groups with regard to self-evaluation of cognitive functioning problems; the mean rating was 3.60,SD = 2.81, in patients with IDH1-mut tumours vs. 3.67, SD = 2.95 in patients with IDH1-wt (U = 579.000, z = 0.18, p = 0.857); 40 (53%) patients with IDH1-wt tumour gave a self-assessment of 0–3 vs. 8 (53%) patients with IDH1-mut, score 4–6 was given by 18 (24%) vs. 5 (33%) patients and a score above 7 17 (23%) vs. 2 patients (13%). We also compared demographic characteristics in patients with and without MGMT promoter TABLE 6. Patient characteristics regarding methyl guanine methyl transferase (MGMT) methylation MGMT-unmet (N=54) MGMT-met (N = 36) Result of the statistical test and effect size Age mean (min/max/SD) 58.94 (31 / 84 / 10.42) 1 58,53 (30 / 78 / 12.67) t = - 0.17, df = 88, p = 0.86 Sex (female / male) 19 / 35 14 / 22 χ2(1) = 0.13, f = 0.04, p = 0.721 Education level (≤9 years /10–13 years / 14–19 years / ≥ 20 years) 8 / 19 / 11 / 0 9 / 29 / 15 / 2 τb (3) = -0.03, z = -1.41, p = 0.776 KPS (70/80/90/100) 20 / 23 / 9 / 2 12 / 14 / 9 /1 τb (3) =0.06, z = 2.82, p = 0.541 WHO grade (III / IV) 3 / 51 9 / 27 χ2(1) = 7.07, f= -0.28, p = 0.008 Corticosteroids mg (min/max/SD) 5.67 (0 /24 / 5,04) 5.48 (0 / 16 / 4.22) t = 0.18, df = 88, p = 0.857 Biopsy/reduction/gross tumour resection 9 / 31 / 14 2 / 18 / 16 χ2(2) = 4.62, V = 0.23, p = 0.099 Tumour location (frontal / temporal / parietal / occipital / diffuse / central) 26 / 20 / 21 / 4 / 2 / 2 8 / 1 / 5 / 0 / 1 / 0 NA Hemisphere (right / left / both) 28 / 40 / 7 10 / 4 / 1 χ2(2) = 4.46, V = 0.223, p = 0.107 IDH1 (yes / no) 5 / 49 10 / 26 χ2(1) = 5.33, f = 0.24, p = 0.021 IDH1 = isocitrate dehydrogenase 1; MGMT-met = methyl guanine methyl transferase promoter methylation; MGMT-unmet = methyl guanine methyl transferase absence of promoter methylation; KPS = Karnoffsky performance status; SD = standard deviation TABLE 7. Cognitive functioning regarding methyl guanine methyl transferase (MGMT) methylation MGMT-met MGMT-unmet Result of the statistical test MGMT-met MGMT –unmet Result of the statistical test N Mean Z score (SD) N Mean Z score (SD) % of impaired % of impaired TMT A 26 2.67 (3.01) 42 3.03 1 (3.90) U = 530.000, z = -0.20, df = 67, p = 0.840 69 66 χ2(1) = 0.08, V = 0.03, p = 0.782 TMT B 20 3.22 (2.30) 26 2.48 1 (3.37) U = 334.000, z = 1.64, df = 45, p = 0.101 86 74 χ2(1) = 1.88, V = 0.14, p = 0.170 SCOWA 33 -1.25 (0.87) 48 -1.18 1 (0.89) U = 756.000, z = -0.35, df = 70, p = 0.729 50 44 χ2(1) = 0.27, V = 0.05, p = .605 SVLT-ir 32 -1.85 (1.27) 48 -1.82 1 (1.01) U = 771.000, z = 0.03, df = 78, p = 0.975 64 67 χ2(1) = 0.01, V = 0.01, p = 0.928 SVLT-sr 32 -2.03 (1.32) 48 -2.06 (1.32) t = 0.09, df = 78, p = 0.926 75 81 χ2(1) = 0.54, V = 0.08, p = 0.460 SVLT-dr 32 -1.98 (1.52) 48 -1.89 (1.25) t = -0.30, df = 78, p = 0.763 66 61 χ2(1) = 0.29, V = 0.06, p = 0.592 SVLT- recog 32 -2.731 (4.24) 48 -2.72 1 (2.71) U = 784.000, z = 0.828, df = 78, p = 0.407 58 61 χ2(1) = 0.07, V = 0.03, p = 0.792 1 the distribution is significantly non-normal M G M T - m e t = m e t h y l g u a n i n e m e t h y l t r a n s f e r a s e p r o m o t e r m e t h y l a t i o n ; M G M T - u n m e t = m e t h y l g u a n i n e m e t h y l t r a n s f e r a s e a b s e n c e o f p r o m o t e r m e t h y l a t i o n ; S D = standard deviation; SVLT = Shiraz Verbal Learning Test; SVLT-dr = SVLT delayed recall; SVLT-ir = SVLT immediate recall; SVLT-recog = SVLT recognition; SVLT-sr = SVLT short delayed recall; TMT A = Trail Making Test, Part A; TMT B = Trail Making Test, Part B Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 208 methylation. The patients differed in the tumour grade. Despite the predominance of Grade IV tu- mours in our sample, the methylated phenotype was more prevalent in Grade III patients (25% vs. 5%, χ2(1) = 7.067, V = 0.28, 1 – ß = 0.757, p = 0.008). In all other demographic characteristics, the groups were comparable. In the cognitive functioning, there were no dif- ferences in mean z-scores or dichotomized test scores between patients with methylated and un- methylated promoter MGMT (Table 7). There were no statistically significant differenc- es in self-evaluation of cognitive functioning prob- lems; the mean number of impaired results were 4.50 (SD = 1.90) in patients with MGMT un-meth- ylated tumours vs. 4.29 (SD = 1.75), U = 1100.000, z = 1.51, p = 0.251. There were also no differences in the number of tests in which patients achieved an impaired result (U = 1052.500, z = 0.67 , p = 0.501). With the mean 4.69 (SD = 2.31) and 4.54 (SD = 2.07) had 5 (14%) patients with MGMT methylated tumours and 6 (11%) pa- tients MGMT unmethylated tumours at most one impaired result, 2–4 impaired results had 9 (25%) vs. 17 (31%) patients, and on more than 5 tests the results were impaired in 22 (61%) vs. 31 (57%) pa- tients. Discussion High-grade glioma patients are experiencing a number of cognitive functioning problems. In our study we focused on the period following the sur- gical treatment and before commencement of sys- temic treatment. The majority of cognitive problems we found were in the fields of executive functions, visual- motor speed and verbal memory, especially im- mediate and short delayed recall, as well delayed recall. There were the least problems in the field of verbal fluency, but even here more than 40% of pa- tients had an impaired result. Among participat- ing patients, only 12% had an impaired result in up to one measured field, while 60% had impaired results in the majority of the measured domains. The analysis of cognitive test scores expressed as z-values gave conclusions comparable to the ones obtained with the analysis of dichotomized scores. The use of dichotomized scores enabled us to also include in the analyses the results of patients who were unable to complete some tests and so avoiding the overrepresentation of patients with better cognitive functioning in the analyses. These results are in accordance with other stud- ies examining cognitive functions in high-grade glioma patients, but it is noticeable that in our study the proportion of patients presenting with the “impaired” result is higher, possibly due to the fact that our study included the entire cohort of high-grade glioma patients. When comparing the results of different studies, it is necessary to con- sider the use of different criteria for impairment, with the otherwise dominant criterion z< -1.5. 5 In comparison with IDH1-wt patients, patients with IDH1-mut (17%), were significantly younger, had better performance status and more often they had Grade III tumour. This is in line with previous studies. 27 Additionally, the cognitive functioning of pa- tients with IDH1-mut was statistical significantly better in verbal memory and executive functions. Immediate recall, short-delayed and long-delayed recall differ statistically significantly in the analy- sis of interval variables as well as in the analysis of dichotomized variables. Executive functions measured with the TMT B test only in the analysis of dichotomized variables, which may be the re- sult of the fact that a larger proportion of patients were unable to complete this test, therefore, they are not included in the analysis of interval vari- ables. Patients with IDH1-mut tumours achieved impaired results on significantly lower number of tests. These findings are in line with findings of the previous studies. 8,19 According to the MGMT promoter methylation status, the groups did not differ statistically sig- nificantly in demographic data. A statistically sig- nificant difference was found in the expression of MGMT methylation according to the grade of the tumour (75% patients with grade III vs. 34% with grade IV). 28 We did not find differences in any of the analysed fields of cognitive functioning and also not in the number of tests in which patients achieved an impaired result. We intended to include all patients with the di- agnosis of high-grade glioma in the observed pe- riod in Slovenia. Given that, after surgery in one of the two centres in Slovenia, all newly diagnosed patients with gliomas are referred to our institu- tion for evaluation regarding further treatment; it gives us an insight into the entire population of pa- tients with glioma. Data collected on the entire co- hort of patients revealed that a large proportion of high-grade glioma patients is unable to participate in the studies of cognitive functioning. In our case 46% of patients were unable to participate due to poor performance status or other somatic factors. Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 209 The finding that a large proportion of patients are unable at all to participate in cognitive func- tioning studies additionally indicates an over- representation of patients with better cognitive functioning in research. From this point of view the cohort study design corresponds better to the everyday clinical practice with the patients with high grade glioma. Patients’ self-assessments on a 1–10 scale did not correlate with the results of the tests used and probably should not be used for any assessment of cognitive functioning; we only found a weak correlation between self-assessment on a 10-point scale and objective assessment. With otherwise different methodology, foreign studies also came to similar results - there is no or weak correlation between subjective assessment and psychological tests. 29 The limitation of our study is lack of data on cognitive functioning prior to surgical treatment. Thus, in the study we did not include eventual dif- ferences between patients with IDH1 mutated and wildtype tumours, which may be present even be- fore surgery 19,30 , which would also be important in the light of research findings regarding the differ- ent dynamics of cognitive decline after surgery. 31 Another point worth mentioning is that several papers showed that epilepsy and the use of antie- pileptics is an important factor of neurocognitive functioning. But in our sample, the use of antie- pileptics could not be analysed as virtually every patient has received them following surgery even those without history of seizures; though in these cases they were weaned from antiepileptics at the beginning of oncological treatment. Our study took place during the coronavirus pandemics. Despite this, oncological treatment was not interrupted nor delayed, but in our study, it was connected with the increase of patients re- fusing to participate and with longer time from surgery to the start of treatment due to infections. It is worth to mention that targeting this popula- tion is beyond single institution capabilities. While the cohort study corresponds better to the clinical practice, on the other hand the low number of the mutations, especially in IDH1, is hampering the statistical analysis. When conducting our study, we noted a distinctive lack of prospective data re- garding patients in suboptimal performance sta- tus, thus overestimating cognitive functioning of high-grade glioma patients. Even as we observed the patients in WHO performance status of 2 the number of cognitive patients rose markedly. It is true that the single centre study is limited in its power to demonstrate effect the genetic and molecular changes exert on cognitive functioning in real life scenarios, the reason being rightly, that outside the trials where cognitive functioning is one of secondary outcomes to survival and time to progression where treatment compliance effec- tively excludes patients with more pronounced im- pairments and in reality the cognitive impairment is more widespread in our patients than reported previously, which should be taken into account in designing further studies. Our study has finished recruiting, but the lon- gitudinal part of the follow up is continuing, thus giving us the chance to determine the impact of genetic and epigenetic changes on cognitive func- tioning in patients surviving longer and maybe even determining if cognition can be used as pre- dictive marker for progression. References 1. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, Burger PC, Jouvet A, et al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007;114: 97-109. doi: 10.1007/s00401-007-0243-4 2. Smrdel U, Popovic M, Zwitter M, Bostjancic E, Zupan A, Kovac V, et al. Long- term survival in glioblastoma: methyl guanine methyl transferase (MGMT) promoter methylation as independent favourable prognostic factor. Radiol Oncol 2015; 50: 394-401. doi: 10.1515/raon-2015-0041 3. Millward CP, Brodbelt AR, Haylock B, Zakaria R, Baborie A, Crooks D, et al. The impact of MGMT methylation and IDH-1 mutation on long-term outcome for glioblastoma treated with chemoradiotherapy. Acta Neurochir 2016; 158: 1943-53. doi: 10.1007/s00701-016-2928-8 4. Kurdi M, Shafique Butt N, Baeesa S, Alghamdi B, Maghrabi Y, Bardeesi A, et al. The impact of IDH1 mutation and MGMT promoter methylation on recurrence-free interval in glioblastoma patients treated with radiotherapy and chemotherapeutic agents. Pathol Oncol Res 2021; 27: 1609778. doi: 10.3389/pore.2021.1609778 5. Sinha R, Stephenson JM, Price SJ. A systematic review of cognitive function in patients with glioblastoma undergoing surgery. Neuro-oncology Pract 2020; 7: 131-42. doi: 10.1093/nop/npz018 6. Van Kessel E, Emons MAC, Wajer IH, Van Baarsen KM, Broekman ML, Robe PA, et al. Tumor-related neurocognitive dysfunction in patients with diffuse glioma: a retrospective cohort study prior to antitumor treatment. Neuro- Oncology Pract 2019; 6: 463. doi: 10.1093/nop/npz008 7. Taphoorn MJB, Klein M. Cognitive deficits in adult patients with brain tumours. Lancet Neurology 2004; 3: 159-68. doi: 10.1016/S1474- 4422(04)00680-5 8. Jütten K, Mainz V, Gauggel S, Patel HJ, Binkofski F, Wiesmann M, et al. Diffusion tensor imaging reveals microstructural heterogeneity of normal- appearing white matter and related cognitive dysfunction in glioma pa- tients. Front Oncol 2019; 9: 536. doi: 10.3389/fonc.2019.00536 9. Van Kessel E, Snijders TJ, Anniek ·, Baumfalk E, Ruis C, Van Baarsen KM, et al. Neurocognitive changes after awake surgery in glioma patients: a retrospective cohort study. J Neurooncol 2020; 146: 97-109. doi: 10.1007/ s11060-019-03341-6 10. Meyers CA, Hess KR. Neuro-oncology multifaceted end points in brain tumor clinical trials: cognitive deterioration precedes MRI progression. Neuro-Oncology2003; 5: 89-95. doi: 10.1093/neuonc/5.2.89 11. Armstrong CL, Goldstein B, Shera D, Ledakis GE, Tallent EM. The predictive value of longitudinal neuropsychologic assessment in the early detection of brain tumor recurrence. Cancer 2003; 97: 649-56. doi: 10.1002/cncr.11099 Radiol Oncol 2023; 57(2): 201-210. Skufca Smrdel AC et al. / Cognitive functioning in high grade glioma patients 210 12. Flechl B, Sax C, Ackerl M, Crevenna R, Woehrer A, Hainfellner J, et al. The course of quality of life and neurocognition in newly diagnosed patients with glioblastoma. Radiother Oncol 2017; 125: 228-33. doi: 10.1016/j. radonc.2017.07.027 13. Johnson DR, Sawyer AM, Meyers CA, Patrick B, Neill O’ , Wefel JS. Early meas- ures of cognitive function predict survival in patients with newly diagnosed glioblastoma. Neuro Oncol 2012; 14: 808-16. doi: 10.1093/neuonc/nos082 14. Meyers CA, Hess KR, Yung WKA, Levin VA. Cognitive function as a predictor of survival in patients with recurrent malignant glioma. J Clin Oncol 2000; 18: 646-50. doi: 10.1200/JCO.2000.18.3.646 15. Lee ST , Park CK, Kim JW , Park MJ, Lee H, Lim JA, et al. Early cognitive function tests predict early progression in glioblastoma. Neuro-oncology Pract 2015; 2: 137-43. doi: 10.1093/nop/npv007 16. Butterbrod E, Synhaeve N, Rutten GJ, Schwabe I, Gehring K, Sitskoorn M. Cognitive impairment three months after surgery is an independent predic- tor of survival time in glioblastoma patients. J Neurooncol 2020; 149: 103- 11. doi: 10.1007/s11060-020-03577-7 17. Derks J, Kulik S, Wesseling P, Numan T, Hillebrand A, van Dellen E, et al. Understanding cognitive functioning in glioma patients: the relevance of IDH-mutation status and functional connectivity. Brain Behav 2019; 9: e01204.doi: 10.1002/brb3.1204 18. van Kessel E, Snijders TJ, Baumfalk AE, Ruis C, van Baarsen KM, Broekman ML, et al. Neurocognitive changes after awake surgery in glioma patients: a retrospective cohort study. J Neurooncol 2020; 146: 97-109. doi: 10.1007/ s11060-019-03341-6 19. Wefel JS, Noll KR, Rao G, Cahill DP. Neurocognitive function varies by IDH1 genetic mutation status in patients with malignant glioma prior to surgical resection. Neuro Oncol 2016; 18: 1656-63. doi: 10.1093/neuonc/now165 20. Bunevicius A, Miller J, Parsons M. Isocitrate dehydrogenase, patient-report- ed outcomes, and cognitive functioning of glioma patients: a systematic review. Curr Oncol Rep 2020; 22: 120. doi: 10.1007/s11912-020-00978-9 21. Weller J, Tzaridis T, Mack F, Steinbach JP, Schlegel U, Hau P, et al. Health- related quality of life and neurocognitive functioning with lomustine- temozolomide versus temozolomide in patients with newly diagnosed, MGMT-methylated glioblastoma (CeTeG/NOA-09): a randomised, multicen- tre, open-label, phase 3 trial. Lancet Oncol 2019; 20: 1444-53. doi: 10.1016/ S1470-2045(19)30502-9 22. Wang Q, Xiao F, Qi F, Song X, Yu Y. Risk factors for cognitive impairment in high-grade glioma patients treated with postoperative radiochemotherapy. Cancer Res Treat 2020; 52: 586-93. doi: 10.4143/crt.2019.242 23. Herzog A. [Validity and reliability of the new Slovenian Test of Word Learning]. [Slovenian]. [graduation thesis]. Ljubljana: Universty of Ljubljana; 2015. 24. Remšak T. [Development of the Spelling Fluency Test].  [Slovenian]. [gradu- ation thesis]. Ljubljana: Universty of Ljubljana; 2013. 25. Sánchez-Cubillo I, Periáñez JA, Adrover-Roig D, Rodríguez-Sánchez JM, Ríos-Lago M, Tirapu J, et al. Construct validity of the Trail Making Test: role of task-switching, working memory, inhibition/interference control, and visuomotor abilities. J Int Neuropsychol Soc 2009; 15: 438-50. doi: 10.1017/ S1355617709090626 26. Wefel JS, Vardy J, Ahles T, Schagen SB. International Cognition and Cancer Task Force recommendations to harmonise studies of cognitive function in patients with cancer. Lancet Oncol 2011; 12: 703-8. doi: 10.1016/S1470- 2045(10)70294-1 27. Iorgulescu JB, Sun C, Neff C, Cioffi G, Gutierrez C, Kruchko C, et al. Molecular biomarker-defined brain tumors: epidemiology, validity, and completeness in the United States. Neuro Oncol 2022; 24: 1989-2000. doi: 10.1093/ neuonc/noac113 28. Capper D, Mittelbronn M, Meyermann R, Schittenhelm J. Pitfalls in the as- sessment of MGMT expression and in its correlation with survival in diffuse astrocytomas: proposal of a feasible immunohistochemical approach. Acta Neuropathol 2008; 115: 249-59. doi: 10.1007/s00401-007-0310-x 29. Tucha O, Smely C, Preier M, Lange KW. Cognitive deficits before treatment among patients with brain tumors. Neurosurgery 2000; 47: 324-33. doi: 10.1097/00006123-200008000-00011 30. Kesler SR, Noll K, Cahill DP , Rao G, Wefel JS. The effect of IDH1 mutation on the structural connectome in malignant astrocytoma. J Neurooncol 2017; 131: 565-74. doi: 10.1007/s11060-016-2328-1 31. Van Kessel E, Snijders TJ, Anniek·, Baumfalk E, Ruis C, Van Baarsen KM, et al. Neurocognitive changes after awake surgery in glioma patients: a retrospective cohort study. J Neurooncol 2020; 146: 97-109. doi: 10.1007/ s11060-019-03341-6