Neuroendocrine differentiation (NED) of the prostate cancer (PCa) is a carcinoma of prostate containing neuroendocrine (NE) component. According to evidence, NED is present in approximately 40% of cases; sole NE prostate cancer is a case in 0.5-2% of patients. The most reliable marker for NED to time is Chromogranin A (ChA). 

Serum increases in ChA are typical for castration-refractory PCa (CRPC). Given the evidence, ChA is single non-invasive and significant test for NED, therefore it should be accounted for in patients with CRPC. The prognosis in patients with high levels of ChA is significantly worse compared to patients without NED in tumor. 

In course of our study of somatostatin analogues we have obtained the results similar to other scientific groups. Using the somatostatin analogues in patients with CRPC with increased level of ChA would be pathogenetically grounded and allows to reach a PSA-response in ca. 70% of patients. Drawing a conclusion, accounting for NED as a strategic biomarker would be an important scientific direction in studies related to the CRPC. NED-status based good planned studies to CRPC are necessary for further investigation of efficacy and safety of somatostatin analogues.