Comparison of three quantitation methods for PCNA immunostaining: Applicability and relation to survival in 83 astrocytic neoplasms

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Abstract
Recent studies on astrocytic tumours demonstrated a close association between patient prognosis and neoplastic proliferation estimated by such methods as Ki‐67 and bromodeoxyuridine labelling. Novel monoclonal PCNA antibodies and special antigen‐retrieval techniques have the advantage of working on routinely fixed and embedded specimens and thus make the estimation of proliferation simpler. In addition to PCNA‐positive cell count expressed in percentages (PCNA‐LI), we estimated the number of PCNA‐immunopositive cells of 83 astrocytomas in two ways: (1) per mm2 of neoplastic tissue (uncorrected PCNA index); and (2) per mm2 of total neoplastic nuclear area (corrected PCNA index). Both of these methods were reproducible and showed a goad correlation with PCNA‐LI and malignancy grade (I–IV). With quantitation methods 1 and 2, the proliferative status of about 2000 cells could be estimated in about 7–10 min, whereas the PCNA count by PCNA‐LI of 200 cells took approximately the same time. The proliferation indices obtained by all three quantitation methods were highly significantly related to patient prognosis. The corrected PCNA index, having a close association with the neoplastic cellularity, even divided the glioblastoma group (grade IV) into two significantly different prognostic groups in which 56 and 17 per cent of the patients were alive after 1‐year follow‐up. The combination of PCNA immunohistochemistry and morphometry seems to give important prognostic information about astrocytomas independent of the histopathological grade.