Prevalence and prognostic influence of genomic changes of EGFR pathway markers in synovial sarcoma

BACKGROUND: We aimed to study the prevalence and prognostic influence of epidermal growth factor receptor (EGFR) and its downstream effectors in synovial sarcoma (SS). OBJECTIVES AND METHODS: The tissue blocks from 30 patients were obtained. Expression of EGFR and phosphatase and tensin homolog (PTEN) were examined by immunohistochemistry, and mutation status of v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) exon 2, V-raf murine sarcoma viral oncogene homolog B1 (BRAF) exon 15, phosphoinositide-3-kinase, catalytic, alpha polypeptide (PI3KCA) exons 9, 20, and PTEN exons 5-9 were analyzed by direct sequencing. RESULTS: EGFR overexpression and PTEN deletion were found in 63.3% and 46.7% of patients. Sequence analysis failed to demonstrate mutations of KRAS and BRAF. However, an E545A point mutation in exon 9 of PI3KCA was found in 2 of the 30 (6.7%) cases and 4 point mutations in exon 5 (E99K, D106N), intro 6 to exon 7 (AATA(G)), and exon 9 (A359T) of PTEN were found in 2 of the 30 (6.7%) cases. PTEN loss was significantly more frequent in cases of trunk tumors, and the overexpression of EGFR was significantly more prevalent in patients who were 35 or older. CONCLUSIONS: PTEN deletion was associated with poor survival.