Immunohistochemical and prognostic characteristics of multifocal glioblastomas

Multifocal glioblastoma (GBM) represents tumours with multiple distantly separated foci. About 7% from all GBMs are multifocal (Dono et al., 2020). The prognosis and immunohistochemical features of patients with multifocal GBM is not well documented. Thus, the objective of this study was to assess prognostic and immunohistochemical characteristics of multifocal GBM. The study group comprised 146 GBM cases, including 16 multifocal tumours. All tumours were immunostained to detect p53, CD44, PDGFRA, IDH1 R132H, p21, p27, Ki-67, p53 proteins. Descriptive statistical assessment was performed including calculation of 95% confidence interval (CI). For association analysis Mann-Whitney U test was used. Survival was evaluated by Kaplan-Meier method. Multifocal involvement were recognized in 11.0% [95%CI: 5.9–16.1] of GBMs. All multifocal tumours were primary GBMs (IDH1 R132H positive). Multifocality showed statistically significant associations with p27 (p = 0.037) and PDGFRA (p=0.049) expression. Thus, multifocal GBMs are characterized by lower expression of p27 and higher PDGFRA values. There were no any associations regarding other analysed markers. Patients diagnosed with multifocal GBMs had significantly worse survival than those with solitary tumours (log-rank, p = 0.002). Median overall survival (OS) in patients with multifocal GBMs was 3.4 [95%CI: 0–6.9] months compared with a median OS of 8.7 [95%CI: 6.8–10.6] months in patients with solitary tumours. Patients with newly diagnosed multifocal GBM experience significantly worse survival than patients with solitary GBM. Lower p27 and higher PDGFRA expression values were found more frequently in multifocal GBM supporting importance of these proteins in tumour progression and more aggressive behaviour.