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Identification of patients with a low grade glioma with a long-term recurrence-free survival is of clinical value as radiotherapy can be postponed until recurrence. The recurring glioma may increase in malignancy compared to the original tumor, which is possibly related to radiotherapy. We studied proliferation by counting mitotic figures and by MIB-1 labeling, apoptosis by TUNEL and expression of proteins related to cell cycle regulation by immunohistochemical analysis of p53, p21, bcl-2 and bax expression in 48 low grade gliomas. Astrocytomas (A, n = 14) and oligodendrogliomas (O, n = 4) with a recurrence-free survival of more than 9 years after surgery had a signficantly lower p53 index compared to A (n = 18) and O (n = 12) with a histopathologically documented recurrence. Additionally, the recurrence-free A had a higher p21 index. No significant differences were observed in MIB-LI, TUNEL-LI, bcl-2 and bax expression. Initially low grade gliomas and their corresponding recurrences were compared (n = 30). In the gliomas without radiotherapy (n = 15), no differences in mitotic rate, TUNEL-LI, p53, p21, bcl-2 and bax expression were found between primary tumors and their recurrences. Only MIB-LI was higher in the recurrent tumors. In the gliomas with radiotherapy (n = 15) no differences were detected in these parameters between the original tumor and the recurrent tumor except for a higher number of mitoses in the recurrent tumors. We conclude that low grade gliomas with a long-term recurrence-free survival were characterized by a low p53 protein expression and, in the case of A, a higher p21 index. We found no evidence that radiotherapy is involved in changes of proliferation, apoptosis or expression of proteins related to cell cycle regulation in recurring gliomas.

With the introduction of new (immuno-)histochemical techniques it is now possible to assess rates of proliferation and apoptosis in brain gliomas using archival paraffin embedded material. As proliferation and apoptosis are related to tumour growth rate quantification of these processes has prognostic value and is related to tumour grading. In this study we assessed the proliferation rate by measuring the Ki-67 labelling index using the MIB-1 antibody (MIB-LI) and the apoptotic rate using the in situ labelling of DNA strand breaks with TUNEL (TUNEL-LI) in 315 supratentorial gliomas. MIB-LI and TUNEL-LI in astrocytomas (A) where significantly lower compared to anaplastic astrocytomas (AA), glioblastomas (GBM) and oligodendroglial tumours [oligodendrogliomas (O) and anaplastic oligodendrogliomas (AO)]. MIB-LI and TUNEL-LI were significantly lower in AA compared to GBM. In astrocytic tumours MIB-LI and TUNEL-LI appeared to be correlated. As the distinction between A and AA is of clinical value but can be difficult histomorphologically we analysed the prognostic value of MIB-LI and TUNEL-LI in gliomas with particular emphasis on A and AA. MIB-LI below 10% was of prognostic value in A and AA, O and AO but not in GBM on univariate survival analysis. TUNEL-LI was of no prognostic value. With multivariate survival analysis MIB-LI lost prognostic significance in O and AO. Astrocytomas with a gemistocytic component (AG) are similar to A with respect to survival and MIB-LI and TUNEL-LI. MIB-LI is of independent prognostic value in A and AA. Assessment of MIB-LI in A and AA can be used as an aid in distinguishing A and AA. [ABSTRACT FROM AUTHOR]