Incidence and Prognostic Value of Human Epidermal Growth Factor (HER2) in Metastatic Colorectal Cancer A Retrospective Study

Abstract

Background: The human epidermal growth factor receptor 2 (HER2) is a transmembrane receptor tyrosine kinase. Activation of HER2 plays a key role in cell proliferation, inhibition of apoptosis, and tumor progression. Amplification of HER2 has associated with poor prognosis in a number of tumor types as breast and gastric cancers, but the prognostic role of HER2 in colorectal cancer (CRC) remains uncertain. Aim of the work: to detect the incidence and evaluate the prognostic impact of HER2 overexpression in correlation to response to treatment, progression free survival and overall survival on the outcome of patients with metastatic colorectal cancer Materials and Methods: we retrospectively reviewed 70 patients diagnosed as metastatic colorectal cancer synchronous or metachronous and treated from January 2012 to end of December 2016 in Department of Clinical Oncology and Nuclear Medicine, Ain Shams University hospitals, Cairo, Egypt. Eligible patients had their paraffin block collected and tested for HER2 by IHC. Results: out of 70 patients with available parrafin block, population age ranged 20-73 years at time of diagnosis, 49 of these cases were left sided(splenic flexure, descending colon, rectum) while 21were right sided(cecum, ascending, hepatic flexure, transverse colon).. Male to female ratio was 3:4. Mucinous variant presents 27.1%(19 cases).Using a cut-off 6 months 41 of these cases presented with synchronous metastasis while 29 cases presented with metachronous metastasis.HER2 incidence (+2 and+3) was found in 8.57% (6 out of 70 cases).Her2 positivity showed statistical significant with shorter time to progression on both first line of chemotherapy(median PFS 3 months vs. 6 months, p=0.045) and second line of chemotherapy (median PFS 4 months vs.6 months, p=0.036), but no statistical significant as regard OS or clinicopathological factors. Conclusion: HER2 positivity is associated with shorter PFS on second line of chemotherapy (irinotican based) but no difference as regard PFS on first line (oxaliplatin based) or OS in metastatic colorectal cancer larger data needed to confirm this conclusion.