Prognostic implication of histopathological, immunohistochemical and clinical features of oligodendrogliomas: a study of 89 cases

Histopathological, immunohistochemical and clinical parameters were correlated with survival in 89 cases of oligodendroglioma (65 patients with grade II: and 24 patients with grade III of the WHO classification). Median survival time and 5-year survival rate were 3.5 years and 76% for patients with oligodendroglioma grade II and 0.875 years and 23% for patients with oligodendroglioma grade m. The tumor biopsy specimens were immunohistochemically analyzed for Ki 67 (MIB-1), vimentin, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE) and synaptophysin. MIB-1 nuclear labeling index ranged from 0.0% to 33.4%; vimentin-immunoreactive tumor cells were found in 25 cases. MIB-1 nuclear labeling index and vimentin immunoreaction showed a significant statistical correlation to the 5-year survival rate of the patients. Tumors with vimentin expression (n = 25) and/or high MIB-1 labeling index (n = 26) had a poorer prognosis than tumors lacking vimentin expression (n = 57) and/or displaying a low MIB-1 labeling index (n = 56). The expression of immunoreactivity for GFAP (n = 53), NSE (n = 23) and synaptophysin (n = 15) appeared to be of no prognostic relevance. Patients with gross total turner resection (n = 47) had a median survival time and 5-year survival rate of 3.3 years and 84% compared to 1.2 years and 42% for patients with subtotal resection (n = 41). The comparison between patients who underwent surgery alone (n = 53) and those who had surgery plus postoperative radiation therapy showed no significant survival benefit from postoperative radiation therapy. In conclusion, tumor grade, MIB-1 labeling index, expression of vimentin and the extent of surgery are shown to be of prognostic relevance for patients with oligodendroglioma.