Expression of Wilms' tumor gene (WT1) is associated with survival in malignant pleural mesothelioma

Calretinin and Wilms' tumor gene (WT1) are mesothelial markers routinely used to confirm the diagnosis of malignant pleural mesothelioma (MPM). We investigated the prognostic value of calretinin and WT1 expression in predicting survival in a series of patients diagnosed with MPM in our institution.

Fifty-two patients diagnosed of MPM were retrospectively reviewed. Calretinin and WT1 were stained for IHC analysis in formalin-fixed, paraffin-embedded sections and positivity was considered for tumors with >1 % of tumor cells stained. Survival data were calculated by the Kaplan-Meier method and Cox regression was used to evaluate the prognostic value of the variables.

Calretinin IHC expression was positive in 83.7 % of patients and WT1 in 78.1 %. A significant association of calretinin and WT1 expression with epithelial histology was detected (p = 0.030 and p = 0.010). We found a significant increase in OS in patients with epithelial subtype, PS1 and neutrophil-lymphocyte ratio (NLR) ≤5 (p < 0.05). In the IHC markers analysis, we found a significant increase in OS for patients with WT1 positive expression (16.4 vs. 2.3 m, p = 0.013), but not differences for calretinin expression (16.6 vs. 5.0 months, p = 0.37). In the multivariate analysis, epithelial histology and WT1 remained as significant prognostic factors for survival (p = 0.004 and p = 0.010, respectively).

In our series of 52 MPM patients, epithelial histology, PS, NLR and WT1 expression are significant prognostic factors for survival. We concluded that WT1, but not calretinin, is a useful prognostic factor in MPM. The role of WT1 assessment is worth of prospective validation in future studies on MPM.