High-grade gliomas and Lynch syndrome: A retrospective descriptive study with a literature review

High-grade diffuse gliomas in adults are common malignant primary tumors of the central nervous system. The association with Lynch syndrome (LS) is documented but remains under-researched. However, there are implications for prevention, genetic counseling, and therapeutic approaches. The objective of this study is to conduct a descriptive cohort of patients with high-grade glial tumors in the context of LS.

We included adult patients with glioblastoma (GBM) or grade 4 astrocytoma (WHO 2021 classification) associated with LS, diagnosed at Lille University Hospital or Valenciennes Hospital between 2014 and 2022. We retrospectively collected clinical, radiological, histopathological, molecular, and therapeutic data.

We included 6 GBM cases with a median age of 58.7 years (IQR 32.4-63.3). Five cases had MSH2 mutations, and one had PMS2 mutation. In one case, MMR protein expression was preserved, and the RER phenotype showed low microsatellite instability. Loss of ATRX expression, overexpression of p53, and giant cells were observed in 50%, 83%, and 66% of cases, respectively. TP53 mutations were found in all cases, and PTEN mutations in 4 cases. Immunotherapy was given to two cases. The 24-month overall survival rate was 50%.

GBMs associated with LS exhibit specific histopathological and molecular biology characteristics that may guide syndrome-related research. These tumors could represent a particular subclassification, potentially leading to specific therapies such as immunotherapy. We propose with a review of case in the literature an algorithm for investigating LS upon discovering a GBM. These exploratory results need to be confirmed by a larger cohort.