Does a low frequency of P53 and Pgp expression in familial glioma compared to sporadic controls indicate biological differences?

Background: A three-fold increased risk for glioma among first degree relatives (FDR) to glioma patients has previously been shown. This study compared familial cases with sporadic controls of glioma to see if phenotypic differences could be detected. Different pathways to tumour growth and progression were investigated including cell cycle regulating genes (p53) and growth factors (epidermal growth factor receptor, EGFR), angiogenesis (vascular endothelial growth factor, VEGF and microvessel density, MVD), pathways of detoxification (glutathione-S-transferase, GST pi) and multidrug resistance (P-glycoprotein, Pgp).
Materials and Methods: Thirty-seven cases of familial gliomas, identified in a population-based study, were compared to 58 sporadic glioma controls chosen with a negative family history of glioma. The immunohistochemistry was performed with standard procedures using the LABSA kit (Zymed lab).
Results: Familial cases had significantly more frequent p53- and Pgp-negative tumours, also when correcting for age, sex and histopathology. However, Pgp was no longer significant after correcting for p53 status indicating a correlation between Pgp and p53. A significant difference between VEGF-negative to VEGF-positive tumours (low- or high-grade) was shown, but it was no longer significant when correcting for p53 status.
Conclusion: Our study investigated phenotypic differences of familial glioma compared to sporadic control. Our finding of a distinct pattern of increased p53- and Pgp-negativity among cases warrants further investigation.