Positive Expression of Paired Box 5 (Pax5) was Associated with Age, Tumor Location, and Tumor Size of Patients with Gastrointestinal Neuroendocrine Tumors (NETs)

Background: Neuroendocrine tumors (NETs) can occur in most human epithelial organs, however, there are few studies on digestive system NETs.Aims: The study aims to analyze Pax5 expression in digestive tract NETs and discuss its diagnostic significance.Methods: This study included 64 cases of NETs diagnosed from 2019 to 2020. Expressions of paired box 5 (Pax5), CD56, synaptophysin (Syn), and chromogranin (CgA) were detected using the immunohistochemical assay. Clinicopathological parameters, including tumor location, histological classification, depth of infiltration, tumor diameter, lymph node metastasis, vascular tumor thrombus, and nerve invasion, were determined in Pax5 positive and negative patients. Spearman correlation analysis was performed to analyze the correlation between Pax5 and CD56, Syn, and CgA.Results: The positive rate of Pax5 expression in patients with NETs was 46.9% (30/64). There were more patients 137;¥60 years illustrating positive expression of Pax5 compared to those patients <60 years (χ²=8.438, P=0.004). There were significant differences in histological classification between Pax5 positive expression patients and Pax5 negative expression patients (χ²=17.639, P=0.011). Significant Pax5 positive expression patients demonstrated tumor size 137;¥3 cm, compared to Pax5 negative expression patients (χ²=6.764, P=0.009). Therefore, positive Pax5 expression was related to age, histological classification, and tumor size of NETs patients. Pax5 expression in digestive system NETs was not correlated with CD56 (χ²=0.233, r=0.024, P=0.853), Syn (χ²=0.635, r=0.047, P=0.715), CgA (χ²=2.346, r=0.170, P=0.179).Conclusion: Positive expression of Pax5 was related to age, tumor location, and tumor size of NETs patients. Pax5 can be used in combination with common immune markers (CD56/Syn/CgA) and can improve the diagnostic accuracy of digestive system NETs.