Can tissue biomarkers reliably predict the biological behavior of craniopharyngiomas? A comprehensive overview

Abstract

Background: The growing interest in the molecular and genetic alterations of craniopharyngiomas (CPs) is embodied in recent studies revealing insights into the CP tumorigenesis and identifying novel molecular pathways amenable of targeted therapies. The actual impact of this new information, however, remains inconclusive.

Methods: We present a comprehensive review of the accumulated knowledge on molecular biology of CPs and a critical analysis on the strengths and weaknesses of the studies focused on CP molecular/genetic alterations published to date.

Results: A thorough analysis of the alterations of β-catenin/CTNNB1 and BRAF genes investigated in 1123 CP cases included in 27 studies, showed that, on average, CTNNB1 mutations were present in two-thirds of adamantinomatous CPs and BRAF mutations in 90% of papillary CPs. Their role as oncogenic drivers has not been well established. Although rare, coexistence of both mutations may occur. The involvement of pituitary stem cells in human CP tumorigenesis is still uncertain. Expression of stem markers in human CP samples predominantly occurred along the CP border in contact with brain tissue. Finally, none of the various molecular alterations which have been proposed as markers for CP recurrence can be used today as reliable predictors of the CP behavior.

Conclusions: The isolated evaluation of CPs' molecular or genetic profiles that do not take into consideration fundamental pathological and therapeutic factors, specifically the tumor topography and the degree of tumor removal, may actually generate confusion regarding the reliability of some biomarkers to predict the CP biological behavior.

Keywords: Biomarkers; Craniopharyngioma; Ki-67; Recurrence; Topography; β-Catenin.