Focal neuroendocrine differentiation lacks prognostic significance in prostate core needle biopsies

PURPOSE: The biological behavior of prostate cancer is highly variable and cannot sufficiently be predicted by histological criteria alone. New prognostic factors are needed in core needle biopsies before initial treatment decisions. We investigate the prognostic significance of focal neuroendocrine differentiation in core needle biopsies of prostate cancer. MATERIALS AND METHODS: Core needle biopsies from 105 untreated patients (mean age 71 years) were immunohistochemically examined for focal neuroendocrine differentiation using an antibody against chromogranin A. Tumor cell proliferation was assessed with Ki-67 labeling index using MIB 1 antibody. The cause of death was determined by examination of records including autopsy reports. RESULTS: Focal neuroendocrine differentiation was found in 25% of the tumors. There was no association between the presence of focal neuroendocrine differentiation and Gleason score or Ki-67 labeling index. Tumor specific survival analysis revealed that high Gleason score and high Ki-67 labeling index were predictors of tumor specific death, whereas focal neuroendocrine differentiation failed to provide prognostic information. There was a significant increase in frequency and density of neuroendocrine differentiation between initial core needle biopsies and later specimens of secondary hormone resistant prostate cancer in 15 patients. CONCLUSIONS: In contrast to high Gleason score and high Ki-67 labeling index, focal neuroendocrine differentiation is not a prognostic factor in core needle biopsies of prostate cancer. Focal neuroendocrine differentiation seems to appear more frequently and intensively in hormone resistant prostate cancer, supporting a role of neuroendocrine cells in the development of hormone refractory disease.