Prognostic Value of Epidermal Growth Factor Receptor in Colorectal Carcinoma

Abstract

Introduction: Colorectal carcinoma is a common malignancy with a worldwide distribution. AJCC tumour staging is the single most important prognostic indicator which is also used for selecting cases for postoperative adjuvant therapy. However, a considerable number of curatively treated colon cancer patients ultimately develop disease recurrence prompting the need to identify additional prognostic markers. Extensive research into the biology of colorectal cancer has identified some molecular markers such as Epidermal Growth Factor Receptor (EGFR) which, in addition to providing an insight into the carcinogenesis of colorectal carcinoma, also provide prognostic information. Aim: To evaluate the prognostic value of expression of EGFR in colorectal carcinoma by correlating it with established prognostic markers such as grade and stage of the tumour. Materials and Methods: Retrospective cohort study of 100 cases of colorectal carcinoma who underwent radical surgery at a large tertiary care hospital was done. Relevant clinical data of the cases was collected from medical records. Histopathologic evaluation of tumour grade, depth of invasion, number of lymph nodes involved and pathologic stage was done. Immunohistochemistry (IHC) was performed for assessment of EGFR expression, which was categorised as positive if >1% of the tumour cells showed EGFR immune-specific membranous brown staining. Expression of EGFR was correlated with the tumour site, histological grade and the pathologic stage by chisquared test (χ2 ). Values were considered significant at p<0.05. Results: Among the stage I and stage II tumours, 18% and 31%, respectively, were positive for EGFR, while among the stage III and stage IV tumours, 74% and 80%, respectively, were positive for EGFR. A highly positive and significant correlation (p<0.01), along with a linear association was noted between the pathologic stage and the EGFR expression of the tumours. No significant association was noted between either the expression of EGFR and the histological grade (p=0.51) or the expression of EGFR and the site of tumour (p=0.10). Conclusion: Epidermal growth factor receptor, due to its strong correlation with the pathologic stage of colorectal carcinoma, can be of prognostic significance. This may have a role in selecting those patients who are at high risk for disease progression and therefore are likely to benefit from adjuvant therapy.

Keywords

• colorectal neoplasms
• molecular markers
• tumour grade