Tyrosine kinase expression in pulmonary metastases and paired primary tumors.

Tyrosine kinase inhibitors against the receptors of vascular endothelial growth factor (VEGFR), epidermal growth factor (EGFR) and the platelet derived growth factor (PDGFR) are increasingly used in the treatment of progressive cancers. However, the expression of these receptors especially in lung metastases has not been examined. Tissue specimen from 35 lung metastases of 33 patients with renal cell carcinoma (n=8), sarcoma (n=10), colorectal carcinoma (n=6), otolaryngologic carcinoma (OLC, n=4), testicular and endometrial cancer (n=1 each), malignant melanoma (n=1), adrenal cancer (n=2), malignant fibrous histiocytoma and malignant peripheral nerve sheath tumor (n=1 each) have been immunohistochemically tested for the expression of PDGFR alpha/beta, VEGFR and EGFR. None of the patients had been pretreated with angiogenic inhibitors prior to metastasectomy. PDGFRalpha was expressed in all metastases; 31% stained negative for PDGFRbeta, 86% negative for VEGFR and 45% negative for EGFR. Primary tumors revealed positive staining for PDGFRalpha in 88%, for PDGFRbeta in 59%, for VEGFR in 0% and for EGFR in 18%. Our investigation of a pilot character represents a 'biomarker-based' analysis of pulmonary metastases of different primary tumors; we conclude that an immediate 'tumor profiling' at initial diagnosis should be considered in order to guide tumor therapy individually.