BACKGROUND: Recent studies suggested substantial differences between primary tumors and metastases for EGFR expression in colorectal cancer (CRC). The aim of the study was to correlate the expression of a panel of molecular markers between primary CRC samples and metastases. METHODS: Expressions of EGFR, pEGFR, VEGF, pVEGF, PTEN, pAKT and p21 were analyzed in 28 primary tumors and 32 liver metastases by immunohistochemistry performed on formalin-fixed, paraffin-embedded sections from 46 CRC patients. The molecular profiles were evaluated by tissue micro-array. The correlation between tumor and metastasis biomarker expressions was tested. RESULTS: Among 60 CRC samples, 25% were EGFR positive, 38% were pEGFR positive, 38% were VEGF positive, 48% were pVEGF positive, 70% were pAKT positive and 51% were p21 positive. PTEN was deleted in 39% of cases and absence of p21 expression was found in 49% of cases. A significant correlation was observed between primary tumors and metastases for pAKT (p = 0.037) and pEGFR (p = 0.0002) status. In patients treated with cetuximab-based therapy (n = 18), p21 appeared as a significant predictive factor of response (p = 0.036). CONCLUSION: Biomarkers status may change between primary and metastatic sites in CRC, with potential implications for the identification of patients who are likely to respond to anti-EGFR treatment.
BACKGROUND: Recent studies suggested substantial differences between primary tumors and metastases for EGFR expression in colorectal cancer (CRC). The aim of the study was to correlate the expression of a panel of molecular markers between primary CRC samples and metastases. METHODS: Expressions of EGFR, pEGFR, VEGF, pVEGF, PTEN, pAKT and p21 were analyzed in 28 primary tumors and 32 liver metastases by immunohistochemistry performed on formalin-fixed, paraffin-embedded sections from 46 CRC patients. The molecular profiles were evaluated by tissue micro-array. The correlation between tumor and metastasis biomarker expressions was tested. RESULTS: Among 60 CRC samples, 25% were EGFR positive, 38% were pEGFR positive, 38% were VEGF positive, 48% were pVEGF positive, 70% were pAKT positive and 51% were p21 positive. PTEN was deleted in 39% of cases and absence of p21 expression was found in 49% of cases. A significant correlation was observed between primary tumors and metastases for pAKT (p = 0.037) and pEGFR (p = 0.0002) status. In patients treated with cetuximab-based therapy (n = 18), p21 appeared as a significant predictive factor of response (p = 0.036). CONCLUSION: Biomarkers status may change between primary and metastatic sites in CRC, with potential implications for the identification of patients who are likely to respond to anti-EGFR treatment.
Authors: Jennifer S Lin; Elizabeth M Webber; Caitlyn A Senger; Rebecca S Holmes; Evelyn P Whitlock Journal: Am J Cancer Res Date: 2011-05-15 Impact factor: 6.166