Prognostic role of somatostatin receptor subtypes in human prostate cancer

Abstract

e16120 Background: Neuroendocrine differentiation (NED) in prostate carcinoma (PC) is frequently detected by immunohistochemistry as single cells in conventional adenocarcinoma. NED of PC correlates with poor prognosis and tumor progression during androgen-deprivation therapy. The aim of our study was to correlate the expression of somatostatin receptor (SSTR) 1, 2, 3, 4, 5 subtypes in primary PC with NED pattern and Overall Survival (OS). Methods. PC tissues were reviewed from 100 pts who had undergone biopsy or radical prostatectomy for previously untreated advanced or metastatic PC from 2002 to 2007. 24 samples expressed hystologically chromogranin A (CgA), a marker of NED expression. Patient characteristics included: median age 68 years (range 45–83), median baseline PSA: 70 ng/ml (range 0.3–200), median ECOG Performance Status: 1 (range 0–2), Gleason score ≥ 7, medium serum level of CgA was 56.2 nmol/L (range 0.5–120). Results: The expression of SSTR subtypes (1, 2, 3, 4, 5) were investigated and our data identified four histological features. SSTR1 was expressed in 4/24 samples, SSTR 5 was detected in 2/24 samples, both SSTR1 and SSTR5 were found in 6/24 samples. OS at last follow up on July 2008 was 60%. SSTR 1–5 were undetectable in 12/24 pts with more aggressive clinical course and the OS was < 10%. The PSA and CgA levels were not correlated with clinical outcome. SSTR subtypes 2, 3 an 4 were not expressed in all 24 samples. Conclusions: SSTRs expression significantly correlated with OS. The absence of SSTR 1 and 5 in more aggressive disease could represent a growth advantage in NED prostate cancer. SSTRs and somatostatin analogs are potential targets for prostate cancer treatment. No significant financial relationships to disclose.