Somatostatin Receptor (SSTR) Expression and Proliferative Index (KI 67) in 100 Patients (PTS) with Gastroenteropancreatic Neuroendocrine Tumors (Gep-Nets). Clinical-Pathological Correlation

ABSTRACT Introduction The expression of somatostatin receptors, mainly subtype 2 and 5 is a characteristic of well-differentiated GEP-NET. Its expression has prognostic and predictive implications for the use of somatostatin analogs. The Ki 67 is a nuclear antigen associated with cell proliferation, present during the cycle phases (G1, S, G2 and M). Objectives To describe the expression of SSTR, and Ki-67 in patients with GEP-NET. To evaluate in this population the correlation between the expression pattern of the 5 SSTR subtypes, Ki-67 and survival. Material and methods We performed the analysis on 100 pts. diagnosed with a GEP -NET, included in the database of Argentum Group. In all cases, was centralized pathology review to confirm the diagnosis. The survival analysis was performed by the Kaplan-Meier method. Log-rank was used to test the comparative analysis of the variables of interest in the study. Results We analyzed 100 pts: 73 pts. Well-Differentiated Endocrine Carcinoma (WDEC), 17 pts Had Well-differentiated neuroendocrine tumors (WDET) and 10 pts. Poorly differentiated endocrine carcinoma (PDEC). Age (median) 54 a. (r 18-84). Primary Location: small intestine 40, pancreas 26 pts. Appendix 9 pts., Stomach 8, rectum 6, unknown 6, colon 4, and esophagus 1 pte. Metastatic disease 76 pts., Localized disease in 24 pts. The expression of SSTR was: Subtype 2 (positive 80 pts.) and subtype 5 (positive 46 pts.). Ki 67 was less than or equal to 2% in 36 pts., between 3 and 15%, 49 pts. and more than 15% in 12 pts. 26/100 pts. had functioning tumors. The analysis included 55 pts. with SSTR 2 / 5 pos. Ki 67 less than or equal to 2% (Group 1), 38 pts. with SSTR 2 / 5 pos and Ki 67 more than 2% (Group 2), 5 pts. with SSTR 2 / 5 neg. Ki 67 less than or equal to 2% (Group 3) and 2 pts. with SSTR 2 / 5 neg and Ki 67 more than 2% (Group 4). Univariate analysis showed significant differences for the expression of SSTR 2 (p. 009), and Ki 67 (p. 001). Survival was higher in Group 1 versus Group 2, median OS was 97 months vs 49 months, and 36 to 23 months, in groups 3 and 4 respectively (p. 0001). Conclusions In this population of pts with GEP-NET we could identify a subgroup of better prognosis associated with expression of SSTR 2 / 5 and Ki 67 less than or equal to 2%. The assessment of SSTR 2 and 5 in tissue, and proliferative index are useful tools for evaluating prognosis in this setting. Disclosure All authors have declared no conflicts of interest.