Epidermal growth factor receptor (EGFR) gene promoter methylation and cetuximab treatment in colorectal cancer patients

BACKGROUND: Epidermal growth factor receptor (EGFR) promoter methylation may be responsible for the loss of EGFR expression in neoplastic cells. The primary aim of our study was to verify a possible correlation between EGFR gene promoter methylation and clinical outcome in metastatic colorectal cancer patients receiving chemotherapy with irinotecan and cetuximab. METHODS: Colorectal samples from patients treated with irinotecan-cetuximab were analysed for EGFR promoter methylation and EGFR immunohistochemistry. RESULTS: Fifty-two patients were analysed. Thirty patients (58%) showed EGFR promoter hypermethylation. In EGFR promoter methylated and EGFR promoter unmethylated patients, we observed a partial response in 3 (10%) and 13 (59%) patients, respectively (P = 0.03), progressive disease was obtained in 19 (63%) and 2 (9%) patients, respectively, with EGFR promoter methylated and EGFR promoter unmethylated tumours (P = 0.0001). Median progression-free survival was 2.4 months in patients showing EGFR promoter methylated tumours and 7.4 months for those who had EGFR promoter unmethylated tumours (P<0.0001; Figure 1). Median overall survival was 6.1 months in patients showing EGFR promoter methylated tumours and 17.8 months for those who had EGFR promoter unmethylated tumours (P<0.0001; Figure 2). CONCLUSION: EGFR promoter hypermethylation, after confirmation in larger data set, may represent a valuable asset in further studies investigating EGFR as a therapeutic target in colorectal cancer. British Journal of Cancer (2011) 104, 1786-1790. doi:10.1038/bjc.2011.161 www.bjcancer.com Published online 10 May 2011 (C) 2011 Cancer Research UK