IMP3 expression in biopsy specimens as a diagnostic biomarker for colorectal cancer.

No single biological marker is used in routine diagnosis of colorectal cancer (CRC) in endoscopic biopsies. IMP3 is a good independent prognostic biomarker for CRC. However, the expression of IMP3 in hyperplastic polyp (HP) and adenoma has not yet been studied. Moreover, no studies have established the diagnostic value of IMP3 in biopsies. This study aims to assess IMP3 expression in HP, adenoma, and CRC in resection specimens and to investigate its value in diagnosis of CRC in biopsies. A total of 1328 specimens (633 of polypectomy, 395 surgical resections, 300 biopsies) were retrospectively analyzed. IMP3 expression was observed in 0 of 197 (0%) normal tissues, 0 of 130 (0%) HPs, 14 of 504 (2.8%) adenomas, and 139 of 197 (70.6%) CRCs. IMP3 was found to be overexpressed in CRC compared with adenoma (P<.001). Among the 300 biopsies, 56 were diagnosed as adenoma, and 244 were CRCs. Of the 56 adenoma cases, 22 (39.3%) were confirmed, whereas 34 (60.7%) were diagnosed as CRC in resection specimens. All 244 CRC biopsies were confirmed by resection specimens. IMP3-positive expression was observed in 204 of 300 (68.0%) biopsies, including in 22 of 56 (39.3%) adenomas and 182 of 244 (74.6%) CRCs. All IMP3-positive expressions in the biopsies were finally diagnosed as CRC. Our findings demonstrated that IMP3 is a reliable marker for the diagnosis of CRC in endoscopic biopsies.