EGFR and p53 status of pulmonary pleomorphic carcinoma: implications for EGFR tyrosine kinase inhibitors therapy of an aggressive lung malignancy.

BACKGROUND

Pleomorphic carcinomas of the lung are uncommon malignant tumors composed of carcinomatous and sarcomatous components and are distinguished from other non-small-cell lung carcinomas by a more aggressive clinical course with early distant metastases and far worse survival. Epidermal growth factor receptor (EGFR) and p53 are common genes involved in the pathogenesis of non-small-cell lung carcinomas, but their roles in pleomorphic carcinomas are unclear. The potential clinical activity of EGFR-targeted therapy is also unknown.

METHODS

A total of 42 pleomorphic carcinomas were identified to investigate somatic mutations of EGFR and p53. Genomic DNA was extracted from microdissected cells of paraffin-embedded tumor tissues. Somatic mutations in EGFR (exons 18-21) and p53 (exons 5-8) were examined.

RESULTS

EGFR mutations were detected in 10 of 42 cases. Five of these patients had point mutations in exon 21 majorly with L858R; this mutation was found in both adenocarcinomatous and sarcomatous components in 1 case. The other 5 cases harbored 4 deletions and 1 mutation in exon 19. p53 mutations were found in 12 patients. Notably, identical mutation was observed in carcinomatous and sarcomatous components in 3 patients, and this finding strongly supported the theory of monoclonal histogenesis.

CONCLUSIONS

The occurrence (23.8%) of EGFR mutations, including the exons 19 and 21 mutations observed frequently in our series, suggests that the patients with inoperable pleomorphic carcinomas are likely to benefit from treatment with EGFR tyrosine kinase inhibitors.