PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA) IN LOW-GRADE ASTROCYTOMAS -ITS PROGNOSTIC-SIGNIFICANCE

Aims and background: A clear line cannot be drawn between well-differe ntiated and anaplastic astrocytomas, and a subset of low-grade tumors, histologically indistinguishable from the others, behaves similarly t o anaplastic astrocytomas. The proliferative index could aid in the id entification of this subgroup, for which a different therapeutic appro ach would be indicated. Methods: We immunohistochemically evaluated th e proliferating cell nuclear antigen (PCNA) expression in 77 well-diff erentiated astrocytomas, since PCNA has been considered a good prolife ration marker. The prognostic significance of PCNA labeling index (LI) was assessed in univariate and multivariate analysis, taking into con sideration some clinical and histologic factors known to affect progno sis. Results: PCNA immunostaining identified a subgroup of tumors, cha racterized by a LI >5%, with a median survival close to that observed in anaplastic astrocytomas. The survival table of such a group was sig nificantly different from that of the group with a lower LI (p = 0.000 9). Multivariate analysis confirmed that PCNA-LI is an independent pro gnostic factor (p = 0.001). Conclusion: These data suggest that PCNA i mmunostaining can be a useful tool to define the prognosis of low-grad e astrocytomas on routine biopsy material.