Background and purpose: Histological grading is widely used to evaluate the prognosis for patients with astrocytic tumors. Many complimentary methods have been introduced, such as proliferation markers in order to better assess the proliferative potential of these gliomas.
Methods: Archival, paraffin embedded specimens of recurrent astrocytic tumors of varying grades from 22 patients were examined using antibodies against Ki-67 (MIB-1). Labeling indices (LI) were analyzed at the first and second operations and compared with tumor grades, age of the patients and the time between the operations as well as the survival time.
Results: There was a progression of malignancy between the operations. Dividing Ki-67 labeling indices in < or = 10% vs. > 10% significantly separated parameters such as the time between the first operation and relapse as well as the cumulative proportion of survival. The proliferation fraction was an independent prognostic factor.
Conclusion: Assessment of Ki-67 LI is highly recommended in addition to histology in evaluation of the malignancy potential of astrocytic tumors.