was isolated from paraffin embedded samples from 84 patients. The DNA methylation status of CpG islands at the MGMT promoter was determined by methylation specific Deforolimus AP23573 polymerase chain reaction as previously described, with some modifications. The annealing temperature was 59 C. Low quality DNA yielding uncertain polymerase chain reaction results was discarded. Unmethylated control DNA and methylated control DNAwith bisulfite treatment were used as negative and positive controls, respectively. Polymerase chain reaction products were separated on 8% polyacrylamide gels, stained with ethidium bromide, and examined under ultraviolet illumination. The investigators performing these assays were blinded to clinical information.
Among 84 patients from whom paraffin embedded samples were available for methylation specific polymerase chain reaction, the MGMT gene promoter was methylated in 35 and unmethylated in 43. In the remaining 6 patients, the methylation status could not be determined. Therefore, the percentage of methylation was 44.9%. Clinical profiles according to MGMT gene promoter methylation status are presented in Table 1. Patients were divided into two groups according to MGMT methylation status. No significant differences in clinical variables were found between the two groups. Treatment response MRI with contrast medium was performed in all patients within 48 hours of operation to evaluate the success of surgery. Most patients were followed up with MRI 1 month after radiotherapy and every 3 months during the first 2 years or when disease progression was suspected.
Disease progression was defined as radiologic, neurologic, or clinical findings. Patients with transient progressive lesions within the first 3 months after the end of radiotherapy were regarded as showing pseudoprogression. Radiation necrosis was seen on CT and MRI as a ring enhancing mass with edema and mass effect, findings similar to tumor recurrence. Diagnostic imaging including positron emission tomography or magnetic resonance spectroscopy and/or surgical pathologic features consistent with cerebral RN were also used to define RN. Statistical analysis Progression free survival and OS were measured from the time of surgery to disease progression or death, respectively, or date of last follow up visit, and analyzed using the Kaplan Meier method.
The log rank test was used to compare MGMT promoter methylation status, methylated versus unmethylated MGMT, and to test the significance of the following prognostic variables: age, sex, extent of surgery, total dose of radiotherapy, and performance status. Multivariate analysis was performed using the Cox proportional hazards model. Comparison of patient characteristics was carried out using the chi square test for categoric variables, and p values 0.05 were considered statistically significant. Results Treatment outcome At the time of analysis, 70 patients had died 3 to 50 months after surgery, and 23 patients were alive 21 to 88MGMT gene promoter methylation status were independently significant prognostic factors. The PFS was 14 months for patients with GTR or STR and 7 months for those with partial resection or biopsy. The median PFS times in the methylated, unmethylated, and unknown MGMT gene promoter groups were 18 months, 9