Recently, various studies have shown that insulin-like growth factor II messenger RNA-binding protein-3 (IMP3) is a useful diagnostic marker for malignant lesions and a prognostic marker for poor survival in several kinds of tumors. However, the value of IMP3 as a diagnostic and prognostic marker in intraductal papillary mucinous neoplasm (IPMN) of pancreas has been unclear until now. In this study, we examined IMP3 immunohistochemical expression in 190 resection samples and 15 biopsy samples of IPMN and analyzed the value of IMP3 as a diagnostic and prognostic marker. IMP3 expression was recognized in 71.8% (28/39) of IPMNs with high-grade dysplasia and in 81.3% (26/32) of IPMNs with an associated invasive carcinoma (IPMN-IC), but it was not found in any IPMNs with low-grade dysplasia or in IPMNs with intermediate dysplasia. IMP3 expression was significantly higher in cancerous lesions (IPMN with high-grade dysplasia and IPMN-IC) than in noncancerous lesions (IPMN with low-grade dysplasia and IPMN with intermediate-grade dysplasia), with a sensitivity of 76.1% and a specificity of 100% (P <.001). We also identified a significant difference in IMP3 expression between cancerous lesions and noncancerous lesions in biopsy specimens (P =.027). In IPMN-IC, disease-specific survival was significantly shorter in the high-expression group (>50% tumor staining) than in the low-expression group (≤50% tumor staining; P =.0069). In conclusion, our findings show that IMP3 is a useful diagnostic marker for distinguishing between noncancerous and cancerous lesions and is a valuable prognostic biomarker in IPMN.
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