IMP3 is a biomarker for non-muscle-invasive urothelial carcinoma of the bladder associated with an aggressive phenotype

Bladder cancer is one of the most common malignancies of urinary tract. The current study aimed to investigate the role of insulin-like growth factor II messenger RNA binding protein 3 (IMP3) expression in the prognostic evaluation of non-muscle- invasive urothelial carcinoma of the bladder. Immunohistochemistry (IHC) was carried out to examine IMP3 protein expression in specimens from 183 cases of non-muscle-invasive urothelial carcinoma, 20 cases of muscle-invasive urothelial carcinoma and 20 benign tissues adjacent to cancer tissue. The expression of IMP3 was not detected in the adjacent benign tissues. The expression intensity of IMP3 in muscle-invasive samples was significantly higher than that in non-muscle-invasive urothelial carcinoma specimens (P = .008). IMP3 expression was significantly related with advanced tumor stage (P < .001), advanced tumor grade (P = .004), and tumor recurrence (P < .001) in non-muscle-invasive urothelial carcinomas. Kaplan–Meier analysis showed that IMP3-positive patients had much lower disease-free (P < .001), progression-free (P = .002) and metastasis-free (P = .019) survival rates compared with those with IMP3-negative tumors. By multivariable Cox analysis, we also found that IMP3 expression in non-muscle- invasive urothelial carcinomas proved to be an independent unfavorable prognostic factor of disease-free survival (HR: 2.52; 95% CI, 1.39–4.56; P = .002), progression- free survival (HR: 5.19; 95% CI, 1.54–17.46; P = .008) and metastasis-free survival (HR: 4.87; 95% CI, 1.08–22.02; P = .040). Our results demonstrate that the expression of IMP3 in non-muscle- invasive bladder cancer can serve as an independent predictor that will help recognize the subgroup of patients with a high ability to relapse, progress, and metastasize and who might get the maximum benefit from an early and more aggressive treatment strategy.