Neuroendocrine cells in the prostatic carcinomas after neoadjuvant hormonal therapy

Prostate cancer is a malignant tumor that is likely to increase in incidence in Japan. The most troublesome facet of this tumor is its conversion from a hormone-sensitive status to an insensitive one. Neuroendocrine differentiation may help explain this phenomenon. We studied the prevalence of neuroendocrine cells in prostate carcinoma after androgen ablation therapy. Radical prostatectomy specimens from 28 patients who had undergone neoadjuvant endocrine therapy with luteinizing hormone-releasing hormone analogue were retrospectively studied. Immunohistochemical staining was used to assess the localization of neuroendocrine cells. Neuroendocrine differentiation index, defined as the sum of the immunoreactivity scores of the specimens against anti-chromogranin A and anti-neuron specific enolase antibodies, was developed. Overall, 46.4% and 53.6% of the prostate carcinomas contained chromogranin A and neuron-specific enolase positive cells, respectively. Localization of these neuroendocrine cells in tumors was patchy. Two specific types of neuroendocrine cells were identified: a closed type and an open type based on the location of the neuroendocrine cells. The neuroendocrine differentiation index correlated with tumor grade, but not with tumor stage. The prevalence of neuroendocrine cells in higher grade prostatic carcinoma may help to explain the insensitivity of these cancers to hormonal therapy.