Detection of IDH1 mutations and the status of MGMT promoter on intraoperative fresh tissue section from frameless neuronavigation needle biopsy. Analysis on 17 patients with brain glial tumor ineligible for craniotomy and tumor resection

It is well known that primary and secondary glioblastomas are histologically largely indistinguishable. Therefore, the detection of IDH1 mutations or the status of the MGMT promoter on a simple bioptic sample could be one of major diagnostic and prognostic importance for glial patients that complements clinical criteria for distinguishing secondary from primary glioblastomas and to predict a more favourable prognosis. Currently, biopsy is the method of choice to obtain tissue from intracranial lesions with uncertain neurodiagnostic findings or in deep locations, with a minimal invasive approach. The needle biopsy with frameless neuronavigation could provide a sampling with elevated diagnostic yield and high concentration of DNA, due to the "image-guided" computer assisted technique of needle insertion through the most neurodiagnostic representative tumor area. The freezing of fresh tumor tissue at biopsy could greatly improve the success of DNA extraction. The concentration of the DNA samples can also improved from a withdrawal in an area with high probability of neoplastic cells. The present study reports the results of 17 patients who had undergone frameless image-guided intracranial needle biopsy from April 2008 until July 2010 at Neurosurgery Unit of the "Arcispedale Santa Maria Nuova" of Reggio Emilia. For these patients the molecular determination of MGMT promoter was assessed with the Nested-Methylation Specific-Polymerase Chain Reaction and the screening of mutations in IDH1 e IDH2 genes was performer by polymerase chain reaction (PCR) and direct sequencing on fresh or cryopreserved needle bioptic tissue.