In our study, despite the MGMT promotor being methylated more frequently in tumors expressing TP53, no significant relationship was observed between MGMT and TP53. We also found that in glioblastomas where TP53 was not expressed, treatment with TMZ and additional chemotherapeutic agents was associated with a low rate of tumor recurrence within 1 year, which was significantly different from the rate in patients treated with TMZ alone. This evidence concerns the gene MGMT and glioblastoma.