Epidermal growth factor receptor overexpression in malignant pleural mesothelioma: prognostic correlations.

BACKGROUND

To evaluate epidermal growth factor receptor (EGFR) phenotypic expression and related gene status in malignant pleural mesothelioma (MPM) and to correlate the results with patients' prognosis.

METHOD

Eighty-three cases of MPM specimens were submitted to immunohistochemical (IHC) staining to evaluate the expression of EGFR protein; positive cases were submitted to fluorescence in situ hybridization (FISH) to investigate the gene status. Results were correlated with clinico-pathological characteristics and long-term survival.

RESULTS

Thirty-eight cases (46%) demonstrated a positive IHC reaction [30/57 (52%) epithelial and 8/20 (40%) biphasic whereas sarcomatous MPM were negative]. No association was recorded between EGFR IHC positive staining and age, gender, or asbestos exposure. Three out of 38 (8%) cases submitted to FISH were positive revealing gene amplification or polysomy. Mean follow-up was 15.4  months (range 2-44). Epithelial subtype only was confirmed to affect prognosis (2-years survival rate 40 vs. 18% for non-epithelial subtype, P = 0.042). When epithelial MPM patients were considered, IHC EGFR positive staining was demonstrated to be a negative prognostic factor (2-years survival rate 26 vs. 60% for IHC EGFR negative staining; P = 0.026).

CONCLUSIONS

EGFR overexpression is identified by IHC in 52% of epithelial MPM and is demonstrated to be a factor negatively affecting prognosis. Phenotypic overexpression seems not to be related to gene status alteration.