Influence of HER2 Overexpression on Response to Cetuximab in Patients with Metastatic Colorectal Cancer, Tehran, Iran

Objective: Colorectal cancer (CRC) remains the fourth cause of mortality in the world. HER2, an epidermal growth factor receptor (EGFR) has an influence on prognosis and overall survival in breast and metastatic gastric cancers. We evaluated the prevalence of HER2 positivity among Iranian patients with CRC and determined the response rate to Cetuximab, an EGFR-targeted drug in eligible HER2 positive patients. Methods: HER2 immunohistochemistry staining was carried out in samples of 150 CRC patients and the prevalence of HER2 overexpression was estimated. We also investigated the association of HER2 overexpression with the prognostic factors, overall survival (OS), and progression-free survival (PFS) as well as response to Cetuximab in the patients by reviewing the medical records. Results: The prevalence of HER2 overexpression was 12%. The mean of follow-ups was 40.67 +/- 21.57 weeks in the patients with HER2 overexpression. PFS and OS were lower in HER2 overexpressed patient than other. There was only a borderline relation between the distant metastasis and HER2 expression. Considering the response to Cetuximab, there was a significant difference between HER2 positive and HER2 negative groups. Conclusions: Our study provides further evidence in the effect of HER2 overexpression in CRC patients on the OS, PFS, and response to Cetuximab.