10079-MPC-6 RADIOLOGICAL AND MOLECULAR ANALYSIS OF WHO GRADE 4 BUTTERFLY GLIOMAS WITH A TAILORED SURGICAL APPROACH Open Access

Surgical resection for butterfly gliomas (bG) are still under debate, but recent findings have shown that surgery prolongs survival. However, clinical and molecular background of bG still remains unknown and surgical strategies based on such findings are scarce.

We treated 39 bG patients between 2005 and 2023, including 32 cases of glioblastoma and 5 cases of astrocytoma, WHO grade 4, IDH-mutant. For the validation, we reviewed 968 MRI obtained from the public datasets (UPENN-GBM, n=611; TCGA-GBM, n=255; CPTAC-GBM, n=61; IvyGAP, n=41).

Molecular analyses revealed that 51.3% of TERT promoter mutations, 59.0% of EGFR amplification/gain, 38.5% of PTEN hemi/homozygous, and 51.3% of CDKN2A hemi/homozygous deletion. Sequential radiological imaging before typical bG diagnosis demonstrated that bG harbors two subtypes which are corpus callosum (CC)-type and hemispheric (H)-type. The multisampling of H-type showed that accumulating alterations in the CC lesions than hemisphere, indicating an invasive trajectory from the hemisphere to the CC region. Survival analysis presented that CC-type was significantly poorer overall survival (OS) than H-type (263 days and 691 days, respectively, P = 0.018). The validation cohort also supported the poor survival of CC-type.

Our detail analyses demonstrated the possibility of two subtypes in bG. Unilateral trans-cortical approach from the larger tumor size with CC removal is favored in the H-type. On the other hand, bilateral trans-sulcal and interhemispheric approaches preserving the intact cortex and cingulate gyrus is an alternative for CC-type.