Analysis of MGMT promoter methylation status on intraoperative fresh tissue section from frameless neuronavigation needle biopsy of 25 patients with brain tumor.

Formalin fixation under conditions that adversely affected the quality of the DNA, or indeterminant assay, or extensive tumor necrosis can compromise the genetic analysis of a brain bioptic sample. The success of DNA extraction and Methyl Guanine Methyl Transferase (MGMT) promoter methylation testing could be improved by freezing of fresh tumor tissue at the moment of biopsy. To ensure an increased concentration of the DNA samples the withdrawal should be performed in an area with high probability of neoplastic cells. From May 2007 to January 2011 fifty-two frameless neuronavigation brain needle biopsy were performed at the Neurosurgery Unit of the "Arcispedale Santa Maria Nuova" City Hospital of Reggio Emilia. The "image-guided" neuronavigated protocol sampling provided withdrawal specimens highly correlated with neuroimaging characteristics of the lesions. In this study the Authors report the genetic analysis on 24 cases of freezing fresh tissue from brain needle bioptic sample starting from July 2008. The molecular determination of MGMT promoter was assessed with the Nested-Methylation Specific-Polymerase Chain Reaction on fresh or cryopreserved needle bioptic tissue. The genetic characterization was feasible in all the bioptic samples. The MGMT promoter was methylated in eleven patients, including a brain infection. The diagnostic yield of brain biopsy could be increased by the neuronavigated trajectories and the intraoperative frozen sections. In the future the availability of the molecular-genetic characterization of a brain tumor before open surgery will provide important information for the optimal treatment. The MGMT promoter status analysis on needle bioptic fresh tissue could be available also for that patient not eligible for surgical remotion of the tumor.