Proliferating cell nuclear antigen (PCNA) in low-grade astrocytomas: its prognostic significance

AIMS AND BACKGROUND: A clear line cannot be drawn between well-differentiated and anaplastic astrocytomas, and a subset of low-grade tumors, histologically indistinguishable from the others, behaves similarly to anaplastic astrocytomas. The proliferative index could aid in the identification of this subgroup, for which a different therapeutic approach would be indicated. METHODS: We immunohistochemically evaluated the proliferating cell nuclear antigen (PCNA) expression in 77 well-differentiated astrocytomas, since PCNA has been considered a good proliferation marker. The prognostic significance of PCNA labeling index (LI) was assessed in univariate and multivariate analysis, taking into consideration some clinical and histologic factors known to affect prognosis. RESULTS: PCNA immunostaining identified a subgroup of tumors, characterized by a LI > 5%, with a median survival close to that observed in anaplastic astrocytomas. The survival table of such a group was significantly different from that of the group with a lower LI (p = 0.0009). Multivariate analysis confirmed that PCNA-LI is an independent prognostic factor (p = 0.001). CONCLUSION: These data suggest that PCNA immunostaining can be a useful tool to define the prognosis of low-grade astrocytomas on routine biopsy material.