Somatostatin Receptor 2 and 5 Expressions in Gastroenteropancreatic Neuroendocrine Tumors in Turkey

Abstract

Background: Gastroenteropancreatic neuroendocrine tumors (GNs) are slow growing and although their incidence has increased in recent years, they are relatively rarely seen. Somatostatin analogues are used in the treatment of GNs that express somatostatin receptor (SR). We aimed to investigate the expression of SR2 and SR5 in GNs. Materials and Methods: In this study the expression of SR2 and SR5 was investigated immunohistochemically in 49 cases (26 males, 23 females) diagnosed and graded with GN according to the World Health Organization classification 2010. Results: The percentage of SR2 staining was 91.0% in grade 1, 82.8% in grade 2 and 100% in grade 3. On the other hand, the percentage of SR5 staining was 81.8% % in grade 1, 60.0% in grade 2 and 0% in grade 3. According to the tumor localization, the percentages of SR2 expression were as follows: pancreas 85.7%, stomach 100%, small bowel 70%, appendix 85.7% and rectum 100%. The percentages of SR5 expression were: pancreas 61,9%, stomach 37.5%, small bowel 70%, appendix 71.5% and rectum 66.6%. There was a significant negative correlation between ki67 percentage and SR5 expression (r=-0.341, p=0.016). Conclusions: In this study, GNs were found to highly express SR2 and SR5. Although the expression of SR2 and SR5 changed according to tumor localization, the expression of SR2 was higher than the expression of SR5 in GN. There was a significant negative correlation between ki67 and SR5. Accordingly, SR5 may be a prognostic indicator of GN.

Somatostatin receptor 2 (SSTR2) expression is associated with better clinical outcome and prognosis in rectal neuroendocrine tumors

“…SSTR2 expression was identified in approximately 70% of rectal NETs in the present study. Previous studies demonstrated that SSTR2 expression in a small cohort of rectal NETs (range 3–13 patients) and the majority of them were included as a component of left colon or colorectal NET cohorts 18 , 38 – 41 . The proportion of SSTR2 expression in rectal NETs ranged from 14 to 100% in the previous studies 18 , 38 , 39 , 41 .…”

Diagnosis, Assessment, and Therapeutic Strategy for Colorectal Mixed Adenoneuroendocrine Carcinoma

“…Octreotide and lanreotide, well-known SSA, have high affinity for SSTR-2 and -5. However, it has been reported that SSTR-5 was expressed in 0% of neuroendocrine carcinomas, while it was positive in 81.8 and 60% of G1 and G2 neuroendocrine tumors, respectively [69,70] . Conversely, only a single study showed a 100% SSTR-2 expression rate in gastroenteropancreatic neuroendocrine carcinoma [69] , but this study included only one rectal neuroendocrine carcinoma case, which is inadequate evidence to support the introduction of SSA for neuroendocrine carcinoma components.…”

Pasireotide in the treatment of neuroendocrine tumors: a review of the literature

“…IHC and autoradiography confirmed that SSTRs 1, 2 and 5 were the most frequent receptors in GEP NETs, whereas the expression of SSTR3 was quite variable (Kimura et al 1999, Kulaksiz et al 2002, Papotti et al 2002, Bertherat et al 2003, Reubi & Waser 2003, Yerci et al 2015, Kasajima et al 2017.…”