Objective: Malignant brain tumors, including Glioblastoma Multiforme (GBM), are among the deadliest brain tumors. Given the fact that the expression of the retinoblastoma (RB) gene in malignant tumors can change the tumor behavior, we seek to investigate the alterations of RB expression in brain tumors.

Materials and Methods: The archives of the Pathology Department of Yazd Hospitals were examined, and all the brain tumors diagnosed between 2013 and 2017 were extracted. All paraffin embedded blocks underwent immunohistochemical staining for RB gene expression. Based on a pre-set checklist, demographics data, tumor type, location, and survival status were entered into and analyzed by SPSS version 25. p-value less than 0.05 was considered statistically significant.

Results: Out of 90 blocks studied, 64.4% belonged to male patients and 35.5% to female patients. The frequencies of brain tumors subtypes were non-glioma (45.6%), low grade astrocytoma (14.4%), anaplastic astrocytoma (18.9%) and GBM (21.1%), respectively. The intensity of RB expression was significantly different between men and women (p-value=0.008), and in different subtypes of the tumors (p=0.04). Multivariate analysis revealed that GBM (HR: 9.933, 95% CI 1.888-52.254, p-value=0.007), age >50 (HR: 8.648, 95% CI 5.116-16.406, p-value= 0.0001), female sex (HR:2.139, 95% CI 1.212-3. 775, p-value= 0.09), RB negative tumors (HR:2.502, 95% CI 1.061-5.896, p-value= 0.036) significantly affect patient survival.

Conclusions: There was a significant difference between men and women, and among different subtypes of the brain tumors in terms of RB gene expression. RB expression had a significant effect on patient survival independent from patient’s age, sex, and tumor subtypes.