10012- MPC-2 DIFFERENCE BETWEEN HISTOLOGICAL AND INTEGRATED DIAGNOSES; IMPLICATIONS FOR TREATMENT

Abstract The difference between histological and integrated diagnoses according to WHO2021 is necessary to clarify the disadvantage of not having molecular information, since molecular analysis is currently available only in a few centers and treatment selection for many cases depends on histological diagnosis. We analyzed 70 cases of glioma. Molecular analysis included IDH, ATRX, and p53 by IHC, IDH, TERTp by sequencing, 1p/19q, CDKN2A/B, PDGFRA, EGFR, PTEN by MLPA. The gliomas were histologically classified into astrocytoma (A) (n=5), oligoastrocytoma (OA) (12), oligodendroglioma (O) (7), and glioblastoma (Gb) (46). Molecular analysis classified A into astrocytoma, IDH-mut, grade 2/3 (4) and molecular Gb (1); OA into A, IDH-mut, grade 2/3 (4), O (6) and molecular Gb (2); O into A, IDH-mut, grade 4 (1), O (5) and molecular Gb (1); Gb into A, IDH-mut, grade 4 (2) and Gb, IDH-wt (44). Of the 70 cases, 65 had no significant difference between histological and the integrated diagnoses, however, 5 patients including A (1), OA (2) and O (2) were changed from grade 2/3 to grade 4, which may have a significant implication on the choice of treatment and the necessity for molecular analysis to improve the overall prognosis of glioma is clear. In order to make the histological diagnosis closer to the integrated diagnosis, it is necessary to histologically observe as wide an area of the tumor as possible. In addition, the cases in which the integrated diagnosis reveals an increase in grade should continue to be investigated to clarify the specific histological findings.