Abstract:Objective To detect the expression of IgM in nasopharyngeal carcinoma (NPC) tissues, and to explore its relationships with the clinicopathological characteristics and prognosis of NPC patients. Methods Immunohistochemical streptavidin-biotin-peroxidase complex (SABC) method was used to detect the expression of IgM in the NPC tissues of 92 patients, the pathologically-diagnosed nasopharyngeal inflammatory tissues of 50 cases were taken as controls. The results were analyzed in combination with clinical and pathological data and prognosis of the NPC patients. Results The positive expression rate of IgM in the NPC tissues was 68.48%, which was significantly higher than 24.00% of the nasopharyngeal inflammatory tissues (P < 0.05). The expression of IgM was mainly located in the cytoplasm in the NPC tissues, but in the cell membrane of the nasopharyngeal inflammatory tissues; and the cytoplasm expression mostly appeared in poorly-differentiated squamous cell carcinoma, and the cell membrane expression was mainly observed in the moderately- and well-differentiated NPC and the nasopharyngeal inflammatory tissues. The expression of IgM in the NPC tissues was negatively correlated with T stage and clinical stage (P < 0.05) in the patients with NPC and had nothing to do with local or cervical recurrence or distant metastasis (P > 0.05). The overall survival rate of the NPC patients with positive IgM expression was significantly higher than that of the NPC patients with negative IgM expression (57.14% vs. 27.59%, P < 0.05), but the diseasefree survival rate was not significantly different between the positive IgM expression group and the negative group (P > 0.05). Conclusions IgM is highly expressed in NPC. It is necessary to further study whether the different expression sites of IgM in NPC and different degree of differentiation are related to the function of the protein. The high expression of IgM may be involved in the early pathogenesis of NPC and can be used as an useful indicator for prognosis prediction of NPC patients.