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Aim: The aim was to compare the pathological complete response (pCR) rate at 8 compared to 12 weeks' interval between completion of neoadjuvant chemoradiotherapy (CRT) and surgery in patients with locally advanced rectal cancer. Method: This was a randomized trial which included a total of 330 patients from two institutions. Patients with locally advanced (T3‐4N0M0, TxN+M0) rectal cancer were randomized into 8‐ and 12‐week interval groups. All the patients received long‐course CRT (45 Gy in 1.8 Gy fractions and concomitant oral capecitabine or 5‐fluorouracil infusion). Surgery was performed at either 8 or 12 weeks after CRT. The primary end‐point was pCR. Secondary end‐points were sphincter preservation, postoperative morbidity and mortality. Results: Two‐hundred and fifty‐two patients (n = 125 in the 8‐week group, n = 127 in the 12‐week group) were included. Demographic and clinical characteristics were similar between groups. The overall pCR rate was 17.9% (n = 45): 12% (n = 15) in the 8‐week group and 23.6% (n = 30) in the 12‐week group (P = 0.021). Sphincter‐preserving surgery was performed in 107 (85.6%) patients which was significantly higher than the 94 (74%) patients in the 12‐week group (P = 0.016). Postoperative mortality was seen in three (1.2%) patients overall and was not different between groups (1.6% in 8 weeks vs 0.8% in 12 weeks, P = 0.494). Groups were similar in anastomotic leak (10.8% in 8 weeks vs 4.5% in 12 weeks, P = 0.088) and morbidity (30.4% in 8 weeks and 20.1% in 12 weeks, P = 0.083). Conclusion: Extending the interval between CRT and surgery from 8 to 12 weeks resulted in a 2‐fold increase in pCR rate without any difference in mortality and morbidity. [ABSTRACT FROM AUTHOR]

Extrahepatic bile duct tumors are uncommon, with the majority being adenocarcinomas. Primary neuroendocrine tumors of the extrahepatic bile ducts are extremely rare. Herein, we report a case of the extrahepatic biliary duct primary well-differentiated neuroendocrine carcinoma in a 45-year-old woman. [ABSTRACT FROM AUTHOR]

Endogenous hyperinsulinemia was found in a 38-year-old female patient with recurrent neuroglycopenic symptoms (the glucose level was 25 mg/dL, insulin 43.9 µ/mL, C-peptide 5.54 ng/mL). No lesion was found on imaging tests including enhanced computed tomography (CT) methods performed with a preliminary diagnosis of insulinoma. A suspicious hyperperfusion was present in the pancreatic tail on the perfusion CT examination performed after obtaining approval. The selective arterial calcium stimulation test (SACST) result was consistent with a diffuse disease in the body and tail. The patient underwent partial (75%) pancreatectomy and is now followed up as a diabetes patient on intensive insulin treatment at the postoperative 38th month. The most common cause of endogenous hyperglycemia in hypoglycemia patients is insulinoma. The noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS) is rarely seen in the adult age group. Although invasive, SACST seems to be the most suitable test to differentiate diffuse or multiple disease from insulinoma and to guide the surgery when advanced radiological imaging methods are inadequate to detect the presence of insulinoma. Regarding perfusion CT, it would be more appropriate to wait for comparative data to be put forward in a more consistent manner. When no response can be obtained to medical treatment in NIPHS, partial/total pancreatectomy is the most appropriate treatment option as it enables recovery from the hypoglycemic episodes despite leading to a significant condition like diabetes. [ABSTRACT FROM AUTHOR]

Background: This study aimed to investigate the prevalence and clinicopathological correlates of intestinal endometriosis, amongst other extra-pelvic endometriosis foci, presenting as bowel obstruction in general surgery practice., Methods: A total of 23 female patients (mean ± SD age: 34.9 ± 6.5 years) who underwent abdominal surgery for acute bowel obstruction and received histopathological diagnosis of endometriosis were included in this retrospective case-series study. Data on patient characteristics, obstetric history, preoperative laboratory and imaging findings, preoperative provisional diagnosis, type of surgical intervention and the pathological diagnosis, and postoperative outcomes were recorded., Results: Definitive diagnoses on histopathological work-up involved intestinal endometriosis (52.2%), scar endometriosis (26.0%), ovarian endometriosis (13.0%) and inguinal endometriosis (8.7%). Postoperative complication, reoperation and recurrence rates were 8.7%, 8.7%, and 13.0%, respectively. Intestinal endometriosis, when compared to other extra-pelvic endometriosis foci (scar and inguinal), was associated with significantly higher preoperative platelet counts (332.0(284.0-528.0)vs. 239.0(223.0-370.0) 10 3 /µL, p = 0.010), lower albumin levels (4.0(2.7-4.7) vs. 4.5(4.2-4.9) g/dL, p = 0.029), higher rates of preoperative CT utilization (91.7% vs. 0.0%, p < 0.001) and emergent surgery (83.3% vs. 0.0%, p = 0.001) and longer LOS (median 4.5 (1.0-26.0) vs. 1.0(1.0-1.0) days, p = 0.001) along with a non-significant tendency for higher postoperative complication (16.7% vs. 0.0%) and ICU stay (25.0% vs. 0.0%) rates., Conclusion: Our findings revealed intestinal endometriosis, predominantly in the terminal ileum/appendix, was the most common extra-pelvic cause of acute bowel obstruction. The scar endometriosis, inguinal endometriosis and ovarian endometriosis appeared to be other potential but less prevalent aetiologies in this setting., Competing Interests: Declarations. Ethics approval and consent to participate: This study was conducted in accordance with the ethical principles stated in the “Declaration of Helsinki” and approved by the Bursa Uludag University Clinical Research Ethics Committee (Date of Approval: 08.07.2024, Protocol No: 2024-10-6). Written informed consent was obtained from each subject. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Cytomegalovirus (CMV) colitis is a critical condition associated with severe complications in ulcerative colitis (UC). This study aimed to investigate the diagnostic value of the presence of CMV DNA in intestinal mucosa tissue and blood samples in patients with active UC. This study included 81 patients with exacerbated symptoms of UC. Patient data were obtained from the Hospital Information Management System. CMV DNA in colorectal tissue and plasma samples were analyzed using a real-time quantitative PCR assay. CMV markers were detected using immunohistochemistry and hematoxylin-eosin staining. Immunohistochemistry positivity was observed in tissue samples from eight (9.9%) patients. Only one (1.2%) patient showed CMV-specific intranuclear inclusion bodies. CMV DNA was detected in 63.0% of the tissues (median: 113 copies/mg) and in 58.5% of the plasma samples (median: 102 copies/mL). For tissues, sensitivity and the negative predictive value (NPV) for qPCR were excellent (100.0%), whereas specificity and the positive predictive value (PPV) were low (41.9% and 15.7%, respectively). For plasma, sensitivity and NPV were high (100.0%) for qPCR, whereas specificity and PPV were low (48.6% and 24.0%, respectively). CMV DNA ≥392 copies/mg in tissue samples (sensitivity 100.0% and specificity 83.6%) and ≥578 copies/mL (895 IU/mL) in plasma samples (sensitivity 66.7% and specificity 100.0%) provided an optimal diagnosis for this test. The qPCR method improved patient management through the early detection of CMV colitis in patients with UC. However, reliance on qPCR positivity alone can lead to overdiagnosis. Quantification of CMV DNA can improve diagnostic specificity, although standardization is warranted.

The overall survival of patients with the advanced and recurrent gastric cancer (GC) remains unfavorable. In particular, this is due to cancer spreading and resistance to chemotherapy associated with the epithelial-mesenchymal transition (EMT) of tumor cells. EMT can be identified by the transcriptome profiling of GC for EMT markers. Indeed, analysis of the TCGA and GTEx databases (n = 408) and a cohort of GC patients (n = 43) revealed that expression of the CDH2 gene was significantly decreased in the tumors vs. non-tumor tissues and correlated with the overall survival of GC patients. Expression of the EMT-promoting transcription factors SNAIL and ZEB1 was significantly increased in GC. These data suggest that targeting the EMT might be an attractive therapeutic approach for patients with GC. Previously, we demonstrated a potent anti-cancer activity of the olive leaf extract (OLE). However, its effect on the EMT regulation in GC remained unknown. Here, we showed that OLE efficiently potentiated the inhibitory effect of the chemotherapeutic agents 5-fluorouracil (5-FU) and cisplatin (Cis) on the EMT and their pro-apoptotic activity, as was demonstrated by changes in the expression of the EMT markers (E- and N-cadherins, vimentin, claudin-1) in GC cells treated with the aforementioned chemotherapeutic agents in the presence of OLE. Thus, culturing GC cells with 5-FU + OLE or Cis + OLE attenuated the invasive properties of cancer cells. Importantly, upregulation of expression of the apoptotic markers (PARP cleaved form) and increase in the number of cells undergoing apoptosis (annexin V-positive) were observed for GC cells treated with a combination of OLE and 5-FU or Cis. Collectively, our data illustrate that OLE efficiently interferes with the EMT in GC cells and potentiates the pro-apoptotic activity of certain chemotherapeutic agents used for GC therapy.

Background: This study aimed to investigate the role of long noncoding RNA (LncRNA) expression profiles to predict relapse and 5-FU response in patients with stage I/II colon cancer (CC)., Methods and Results: The expression level of 15 LncRNA was analyzed in stage I/II colon tumors of 126 CC patients. To confirm the findings in-vitro, 5FU-resistant HT29 cells were generated by subjecting HT-29 cells to the increasing concentrations of 5FU for 6 months. The 5FU resistance was observed in WST-1 and Annexin V analyses. The colony formation and wound healing assays were assessed to determine the metastatic properties of the cells. Expression levels of LncRNAs and mRNA of EMT-related genes were determined by RT-PCR. The role of LncRNA on metastasis and 5FU sensitivity were confirmed in pcDNA3.0-PTENP1 and si-MALAT1 expressed 5FU-resistant HT29 cell lineages., Results: High MALAT1 (p = 0.0002) and low PTENP1 (p = 0.0044) expressions were significantly associated with 5-FU resistance and tumor relapse in stage I/II CC. The invasiveness and colony-forming characteristics of 5-FU-resistant cell lineages were higher as compared to the parent HT-29. Moreover, the expression of MALAT1 (p = 0.0009) was increased while the expression of PTENP1 (p = 0.0158) decreased in 5FU-resistant-HT-29 cells. Si-MALAT1 treatment increased cell sensitivity to 5FU, whereas it decreased invasive behaviors of 5 FU-resistant-HT-29 cells., Conclusion: MALAT1 may be a biomarker in predicting recurrence in early-stage CC. Our findings suggest that a cell-based therapy to target MALAT1 could be established for these patients to prevent metastasis and 5-FU resistance., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: Pancreatic neuroendocrine neoplasms (NENs) are tumors with histopathologic and prognostic heterogeneity that pose difficulties in establishing standards for diagnosis, classification, and treatment. Among NENs, well-differentiated neuroendocrine tumors (NETs) have been classified as grade 1, 2, and 3 in the most recently released World Health Organization classification. Although well-differentiated NETs are associated with relatively better prognosis, they have a potential for malignant behavior such as extrapancreatic spread, metastasis, or recurrence. The present study aimed to evaluate clinical and histomorphologic findings of patients with well-differentiated pancreatic NETs and to identify histopathologic findings effective in predicting nodal metastatic progression., Methods: The study group consisted of 54 patients diagnosed with well-differentiated NET. All preparations and blocks of the patients were examined for the following histopathologic parameters: tumor diameter, microscopic tumor growth pattern (solid, trabecular, acinar, and mixed), cellular features (clear, eosinophilic, oncocytic, peliotic, and pseudopapillary), stromal changes (calcification, lymphocytic infiltration, and stromal hyalinization), presence of necrosis, perineural invasion, lymphovascular invasion, mitotic activity, and Ki67 proliferative index., Results: Lymph node metastasis was present in 7 patients. Lymph node metastasis was significantly associated with tumor diameter of >2 cm ( p = 0.012), Ki67 proliferative index of >20% ( p = 0.022), grade 3 tumors ( p = 0.002), presence of dense stromal hyalinization ( p = 0.034), and mild lymphocytic infiltration ( p = 0.041)., Conclusion: The present study revealed that the new findings such as presence of dense stromal hyalinization and absence of remarkable lymphocytic infiltration could be predictive morphologic findings for the development of lymph node metastasis.

The tumor-node-metastasis (TNM) classification, the presence of a mucinous component, and signet ring cells are well-known criteria for identifying patients at a high risk for recurrence and determining the therapeutic approach for early-stage colon cancer (eCC). Nevertheless, recurrence can unexpectedly occur in some eCC cases after surgical resection. The aims of the present study were to evaluate the relation of dysregulated MACC1, c-MET, and NM23-H1 expression with the histopathological features of tumors in recurrence formation in eCC cases. A total of 100 sporadic eCC patients without poor prognosis factors were evaluated in this study. The relationship between the altered expression of MACC1, c-MET, and NM23-H1 and pathological microenvironmental features, including the presence of tumor budding and desmoplasia, were assessed. The primary outcomes, including 5-year overall survival (OS) and disease-free survival (DFS), were also measured. Compared with nonrecurrent patients, the expression level of MACC1 was 8.27-fold higher, and NM23-H1 was 11.36-fold lower in patients with recurrence during the 5-year follow-up (p = 0.0345 and p = 0.0301, respectively). In addition, the coexistence of high MACC1 and low NM23-H1 expression and tumor budding was associated with short OS (p < 0.001). We suggest that the combination of reduced NM23-H1, induced MACC1, and the presence of tumor budding are promising biomarkers for the prediction of recurrence and may aid the stratification of patients with stage II colon cancer for adjuvant chemotherapy., (© 2017 APMIS. Published by John Wiley & Sons Ltd.)

Objectives: Periampullary region tumors (PRTs) are the fifth highest cause of cancer-related deaths worldwide. Although recent studies have highlighted the prognostic value of the long noncoding RNA HomeoboxA transcript at the distal tip (HOTTIP) in patients with pancreatic ductal adenocarcinoma, the relationship between HOTTIP and clinical outcome of all PRTs remains obscure. The aim of this study was to clarify the prognostic significance of HOTTIP in patients with all PRTs related to KRAS mutational status., Methods: HomeoboxA transcript at the distal tip expression was detected in 100 PRT samples using quantitative real-time polymerase chain reaction. The associations between HOTTIP levels, clinicopathological factors, and patient prognosis were also analyzed., Results: The expression of HOTTIP was found to be significantly upregulated by 32-fold (P = 0.031) in tumor tissues compared with normal tissues. The over expression of HOTTIP was related with presence of invasion and metastasis (P = 0.0467, P = 0.0256). In addition, increased HOTTIP expression was associated with poor prognosis independent of KRAS mutation (P < 0.001; n = 72). Moreover, multivariate analysis showed that high HOTTIP expression was an unfavorable prognostic factor for overall survival., Conclusions: Our findings indicate that high levels of HOTTIP expression have the potential to be an independent, unfavorable prognostic factor for patients with PRT.

Objectives: The success of gemcitabine plus radiotherapy is dependent on the mutation status of pancreatic ductal adenocarcinoma (PDAC) tumors in the EGFR and KRAS genes; however, radiotherapy resistance may also be modulated epigenetically by microRNA (miRNA) regulation. In this study, we examined the potential effect of miRNAs on the resistance to radiotherapy in cases without EGFR or KRAS mutation., Methods: The association of EGFR and KRAS mutation status and different expression patterns of 6 selected miRNAs related to the EGFR/KRAS signaling pathway were evaluated in the tumors of 42 patients with PDAC., Results: Reduced miR-216b and miR-217 expression was associated with aggressive tumor characteristics and shortened disease-free survival. In addition, miR-216b expression was reduced 2.7-fold in the cases that did not benefit from therapy, although they did not demonstrate EGFR or KRAS expression (P = 0.0316). A negative correlation between FGFR1 and miR-216b expression (r = -0.355) was found in the tumors of these cases., Conclusions: Further studies and validations are required; in the tumors of patients with PDAC without activating mutations and induced expression of EGFR/KRAS genes, down-regulated miR-216b expression may be associated with a poor response to radiotherapy via deregulation of another signaling pathway related to FGFR1 signaling.

Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare neoplasm that accounts for 2-3% of all primary pancreatic neoplasms. This study aimed to characterize clinicopathological features associated with SPNs and to retrospectively evaluate the relationship of these features with predictive parameters associated with aggressive behavior. We reviewed 16 cases of SPN of the pancreas that had been diagnosed between 2005 and 2014 at our pathology department. A total of 16 cases, 15 female and one male, were evaluated in this study. The patient age ranged from 13 years to 63 years with a median of 35.70 years. The mean tumor diameter ranged from 2 cm to 18 cm with a mean diameter of 5.90 cm. We identified a significant association between the presence of clear cells and perineural invasion (p=0.019), which was considered to be a predictive factor for aggressive behavior. Other features (i.e., localization, nuclear grooves, central hyalinization, myxoid stroma, eosinophilic bodies, foamy histiocyte aggregates, multinucleated cells, and calcification) were not significantly associated with predictive factors for aggressive behavior. One patient died as a result of a pancreatic fistula that developed as a postoperative complication. The remaining 15 patients are alive and have not demonstrated any signs of recurrence or metastasis. The current study suggested that the presence of clear cells might serve as a possible prognostic indicator of perineural invasion, which is a predictive parameter associated with aggressive behavior in SPN., (Copyright © 2016. Published by Elsevier Taiwan.)

Objective: Several studies have demonstrated the importance of mutations in codons 12, 13 and 61 and variations in the 3' untranslated region (3'UTR) of the KRAS gene, frequently observed genetic events in the progression of pancreatobiliary tumors (PBT). However, limited data exist on the clinical effect of these alterations. The aim of the current study was to clarify the frequency of relevant alterations of the 3'UTR regions of the KRAS gene and the effect of KRAS 3'UTR polymorphisms on the prognosis of patients with codon 12, 13 and 61 mutations in a Turkish population with PBT., Methods: Codons 12, 13, and 61 and 3'UTRs of the KRAS gene were screened by single-strand conformation polymorphism (SSCP) analysis and DNA sequencing in 43 patients and 10 controls. Chi-squared and independent sample T tests were used to evaluate the results of the mutation analysis and clinical features of the patients., Results: We defined the c.38G > A (rs112445441, p.G13D) (39.54%) mutation and two 3'UTR variations, c.*4066delA (rs560890523) (23.26%) and c.*4065&#95;*4066delAA (rs57698689) (6.98%), in the KRAS gene of Turkish patients. There was a statistically significant relationship between the c.*4066delA (rs560890523) and c.*4065&#95;*4066delAA (rs57698689) variations and invasion and lymph node metastasis status of the patients (p < 0.001). Compared to patients with c.38G > A (rs112445441, p.G13D), patients with c.*4066delA (rs560890523) and c.38G > A (rs112445441, p.G13D) presented more aggressive tumors with highly invasive features. The present study contributes findings regarding the clinical effects of KRAS alterations in PBT. Based on our study, further investigations are required., (Copyright © 2016 IAP and EPC. Published by Elsevier B.V. All rights reserved.)

Purpose: The clinical value of HER4 - a cell surface receptor that belongs to the human epidermal growth factor receptor family - for predicting survival outcomes in patients with breast cancer remains controversial. Herein, we sought to investigate the prognostic significance of HER4 immunohistochemical expression with respect to progression-free survival (PFS) and overall survival (OS) in Turkish patients with metastatic breast cancer (MBC)., Methods: MBC patients (N=45; mean age=50.5±12.7 years) were consecutively enrolled between 2000 and 2006 in the Department of Oncology at the Uludag University Medical Center, Bursa, Turkey. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded sections. The predictive value of HER4 expression was investigated by multivariate analysis after allowance for potential confounders., Results: The mean PFS in the study participants was 11.35 months (range:1-50), whereas the median OS was 22.18 months (range:1-76). The mean PFS in patients with a HER4 immunohistochemical score of 0, 1+, 2+, and 3+ was 11.0 ± 4.8, 11.3 ± 7.7, 11.7 ± 8.1, and 10.4 ± 7.4 months, respectively (p=0.99) . The mean OS in patients with a HER4 score of 0, 1+, 2+, and 3+ was 13.3 ± 6.8, 25.6 ± 10.8, 22.9 ± 10.7, and 13.5 ± 9.9, months, respectively (p=0.44). The results of multivariate Cox regression analysis indicated that the presence of visceral metastases was the only independent prognostic factor for both OS (HR=3.01, 95% CI=1.56-3.99, p <0.01) and PFS (HR=2.91, 95% CI=1.51-3.78, p <0.01)., Conclusion: HER4 immunohistochemical expression is not an independent predictor of OS and PFS in Turkish MBC patients.

Giant cell tumor of bone (GCTB) is a benign tumor with a tendency for local recurrence. GCTB may cause lung metastases, and secondary malignant GCTB is rare. Its histological appearance does not predict local aggressiveness and/or the metastatic potential of the tumor. We aimed to investigate the prognostic value of the Ki-67 proliferative index and p53 protein expression in GCTB in predicting local recurrence, lung metastasis, and malignant transformation. We retrospectively reviewed 42 cases of GCTB. The p53 expression was positive in 20 cases. We used 10% as a cut-off value for p53 expression. In 10 cases, there were local recurrences. Lung metastases were found in three cases and malignant transformation was found in one case with classical GCTB located in the sacrum three years following diagnosis. The Ki-67 index was higher in cases with recurrence, but this difference was not statistically significant. Of the recurrent cases, two had no p53 staining while eight had moderate-to-strong staining. The staining was usually weakly positive in the non-recurrent cases. In conclusion, we believe that p53 may be used as a marker for the biological behavior of GCTB.

Glomus tumors in the gastrointestinal tract are unusual, as the previous series in the literature have been mainly limited to the stomach. Less than 10 cases of esophageal glomus tumors have been described in the literature. Oncocytic glomus tumors are a recently identified, rare variant of the glomus tumor. We report a 47-year-old female who presented with an approximately 3-month history of dysphagia and weight loss. Upper gastrointestinal endoscopy showed a black-purple, hypervascular, protruding lesion measuring approximately 65 mm at the 37th cm of the esophagus. The patient underwent an Ivor Lewis operation via open thoracotomy. The resected specimen had a protuberant, ulcerated mass measuring 80 × 35 mm in the posterior wall of the esophagus. Based on the histopathological, immunohistochemical and electron microscope findings, the final diagnosis was a malignant glomus tumor with oncocytic features. To our knowledge, this is the first report of a malignant glomus tumor with oncocytic features in an esophageal location., (© 2015 APMIS. Published by John Wiley & Sons Ltd.)

Background: Human adiponectin (ApN), a 30 kDa glycoprotein of 244-amino acids which is predominantly produced by adipocytes, exerts its effects via two receptors, namely adiponectin receptor-1 (adipo-R1) and adiponectin receptor-2 (adipo-R2) with differential binding affinity to globular adiponectin. Adiponectin receptor expression has been studied in several cancer tissues. However, there are no studies of colorectal adenomas which are considered to be precursors for colorectal carcinoma (CRC)., Objectives: In the present study, the expression of adipo-R1 and adipo-R2 was investigated immunohistochemically in colorectal adenomas and colorectal carcinoma tissues in an attempt to determine associations with these tumors., Materials and Methods: The study enrolled 50 CRC patients with tumor resection and 82 patients who were diagnosed with adenomatous polyps, classified as negative for neoplasia, low-grade dysplasia (L-GD) or high- grade dysplasia (H-GD)., Results: Expression of both adipo-R1 and adipo-R2 was found to be significantly lower in the CRCs than in colorectal adenomas (tubular and tubulovillous, p=0.009 and p<0.001, respectively). Adipo-R1 and adipo-R2 expression was also significantly lower in the CRC group when compared with the groups of patients with low grade dysplasia, high-grade dysplasia or no neoplasia (p=0.012 and p<0.001, respectively). In addition, it was observed that adipo-R2 expression was generally positive in the non-neoplastic group irrespective of the adipo-R2 expression. In the L-GD, H-GD and CRC groups, the adipo-R2 result was positive whenever adipo-R1 result was positive but some patients with negative adipo-R1 had positive adipo-R2 (p<0.001, p=0.004, p<0.001, respectively)., Conclusions: This study indicated that ApN may play a role in the progression of colorectal adenomatous polyps to carcinoma through actions on adipo-R1 and adipo-R2 receptors.

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.