IMP3 as a prognostic biomarker in patients with malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma (MPeM) is an incurable cancer with poor prognosis, and several biomarkers have been suggested for screening of MPeM. The aim of our study was to evaluate the prognostic significances of IMP3 and Fli-1 in MPeM. Diagnostic biopsies of 44 MPeM patients were centrally collected and were immunohistochemically analyzed for expression of IMP3, Fli-1, and Ki-67. Labeling was assessed by 2 pathologists. Complete clinical information and follow-up were obtained from patients' records. Carcinomas expressed Fli-1 in 42 (95.5%) of 44 specimens, and IMP3 in 23 (52.3%) of 44 specimens. Spearman ρ analysis revealed that Fli-1 expression was related to both histologic type and Ki-67 labeling index (Ki-67LI; r = −0.500, P < .05; r = 0.358, P < .05), and IMP3 expression was related to Ki-67LI (r = 0.401, P < .05). A Kaplan-Meier analysis and univariate Cox regression analysis showed that tumor-directed treatment, a lower peritoneal carcinomatosis index, stage I, lower Ki-67LI, and lower level of IMP3 expression had a statistically significantly positive effect on overall survival; Fli-1 did not affect overall survival in the univariate analysis (hazard ratio [HR], 1.026; P = .904). A Kaplan-Meier analysis showed the correlation between IMP3-Fli-1 and overall survival, whereas univariate and multivariate Cox regression analyses did not confirm the correlation. Cox regression analysis revealed that IMP3 expression (HR, 2.311 [95% confidence interval, 1.190-4.486]; P = .013) and no tumor-directed treatment (HR, 0.189 [95% confidence interval, 0.086-0.416]; P = .000) retained independent prognostic significance, both with negative effect on OS. IMP3, along with tumor-directed treatment protocols, is a powerful prognosticator in patients with MPeM.