Pathological findings and prognostic factors in recurrent glioblastomas

Glioblastomas, which are the most common primary intracranial tumor, are associated with the poorest survival time, which is typically 1-2 years. Age at initial diagnosis, Karnofsky performance score, and O(6)-methylguanine DNA-methyltransferase (MGMT) promoter methylation status are the most well-documented predictors of survival in patients with newly diagnosed glioblastoma. Few studies have examined prognostic factors in patients with recurrent glioblastomas. At relapse, the pathological features of glioblastomas are affected by tumor regrowth and the influence of chemoradiotherapy during the initial treatment. Morphological transformations at recurrence include quantitative changes in tumor cells, such as the presence of giant cells and gemistocytic cell formation, radiation necrosis, and vascular structural changes. Therefore, we should carefully examine pathological findings at recurrence. In this report, we analyzed MGMT promoter status, the MIB-1 index, and the pathology of tumor samples at the first (primary tumor) and second (recurrent tumor) surgeries and clarified prognostic factors in patients with recurrent cases. In the multivariate analysis, we showed that MIB-1 indexes at the time of the second surgery (p = 0.004) persisted as a significant independent prognostic factor in survival of patients with recurrent glioblastoma.