Somatostatin receptor subtypes 2 and 5 are associated with better survival in well-differentiated endocrine carcinomas

Abstract

The majority of gastroenteropancreatic well-differentiated endocrine carcinomas (WDEC) express somatostatin receptors (SSTR). To correlate the expression of SSTR subtypes by reverse transcriptase-polymerase chain reaction (RT-PCR) with clinicopathological features and survival in a group of WDEC patients, 42 WDEC tissue specimens from 33 patients were analysed. All patients were treated with somatostatin analogues and had a median follow-up period of 45 months (range 6-196). Neither SSTR2 and SSTR5 expression nor Ki-67 level alone correlated with survival. A significantly better survival rate was observed in patients with tumours expressing SSTR2, SSTR5 and Ki-67 <2%, compared to those with SSTR2- and SSTR5-negative tumours and Ki-67 >or=2% (p < 0.038), with 5-year survival rates of 91 vs. 43%, respectively. Expression of SSTR2 and SSTR5 appears to play a positive prognostic role, possibly correlated with the high affinity that the available somatostatin analogues display for these 2 specific SSTR subtypes.