The Clinical Significance Of EGFR And KRAS Protein Expression In Colorectal Polyps

Background and Objective: Colorectal cancer is one of the common gastrointestinalmalignancies. It is generally considered that the development of colorectal cancer gothrough normal intestinal epithelium-proliferative changes/small adenomas-earlyadenoma-interim adenoma-advanced adenoma-carcinoma-cancer metastasis stages.Colorectal adenomas are considered as precancerous lesions. At present, the mostperformed treatment for colorectal polyps is endoscopic polypectomy. It is confirmedthat the endoscopic removal of adenomas can reduce76%to90%of the incidence ofthe colorectal cancer. Clinically5mm or larger colorectal polyps, particularlyadenomatous polyps are usually more actively treated and sent to pathologicalinspection if possible, but those who are not inspected for their good endoscopicmorphology may be delayed in the follow-up because of the potential malignancy; Forsize of lesion locations smaller than5mm, doctors will resect them selectively and sendthem to pathological inspection based on their clinical experience. All of these mayleave part of the smaller polyps with malignant tendency unnoticed during colonoscopy.Because the molecular expression of cancerous polyps appears prior to themorphological change, early and effective using of gene expression to distinguish thepolyps with potential malignancy, especially the polyps without typical adenomatousstructure, timely processing and shortening the follow-up time will play a key role incolorectal cancer prevention. It has been demonstrated that the development ofcolorectal cancer is the results of multiple genes and signal transduction pathwaysdysfunctional accumulation. Abnormal activation of EGFR, Overexpression of K-ras and B-raf-induced genes and their products are considered to be the causes of theoccurance and malignant evolution of colorectal cancer. By detecting the expression ofEGFR and K-ras protein in colorectal polyps in this research, we can discover theirrelationship with clinical parameters of colorectal polyps, and further investigate therole of EGFR and K-ras protein from the protein level during the development ofcolorectal polyps, as well as the feasibility of early-warning markers of the two proteinsas adenomatous evolution and malignant transformation in colorectal polyps.Methods:53cases of colorectal polyps were resected and obtained undercolonoscopy, of which25cases were non-adenomatous polyps and28cases wereadenomatous polyps.115cases of colorectal cancer tissues were obtained by surgicalexcision. Immunohistochemical SP method was used to detect the expression of EGFRand K-ras protein in colorectal polyps and primary colorectal cancer. The two kinds ofprotein expression and its relationship with clinical parameters, as well as the mutualrelationship between the two in the expression of colorectal polyps, were statisticallyanalyzed in SPSS19.0software.Results:1. The EGFR protein expression in the colorectal polyp group (adenomatousand non-adenomatous) and the colorectal cancer group.The expression of EGFR protein in colorectal non-adenomatous polyp group,adenomatous polyp group and colorectal cancer group were32.00%(8/25),64.29%(18/28) and62.61%(72/115), the positive expression rate of adenomatous polyp groupwas higher than that of non-adenomatous polyp group. There existed statistic differencebetween the two groups (P<0.05), and the positive expression rate of colorectal cancergroup was higher than that of non-adenomatous polyp group, there were significantstatistic difference between the two groups (P <0.01), however the positive expressionrate of adenomatous polyp group and colorectal cancer group were close, there were nostatistic significance (P>0.05).2. The relationship between EGFR protein expression in the colorectal polyp groupand the clinical parameters.The EGFR protein expression existed statistic difference between the colorectal non-adenomatous polyp group and adenomatous polyp group (P<0.05), but there wereno statistic significance in male and female groups,<60years and≥60years of agegroups, single and multiple groups, rectum, left colon and right colon groups (P>0.05).3. The K-ras protein expression in the colorectal polyp group (adenomatous andnon-adenomatous) and the colorectal cancer group.The expression of K-ras protein in colorectal non-adenomatous polyp group,adenomatous polyp group and colorectal cancer group were36.00%(9/25),78.57%(22/28) and46.09%(53/115). The positive expression rate of adenomatous polyp groupwas significantly higher than that of non-adenomatous polyp and colorectal cancergroup, there existed significant statistic difference (P<0.005), but there were no statisticdifference between the colorectal non-adenomatous polyp and the colorectal cancergroup (P>0.05).4. The relationship between K-ras protein expression in the colorectal polyp groupand the clinical parameters.The K-ras protein expression existed statistic difference between the colorectalnon-adenomatous polyp group and adenomatous polyp group (P<0.05), but there wereno statistic significance in male and female groups,<60years and≥60years of agegroups, single and multiple groups, rectum, left colon and right colon groups (P>0.05).5. The correlation analysis of EGFR and K-ras protein expression in colorectal polypgroupThe expression of EGFR and K-ras protein in colorectal polyp group showed asignificant positive correlation (P<0.005, r=0.444).Conclusion:1. A certain level of expression of EGFR and K-ras protein does existsin the colorectal adenomatous polyps.2. The increased expression of EGFR and K-ras protein may be related to theoccurance and malignant transformation of colorectal adenomatous polyps.3. EGFR and K-ras protein plays a synergistic role in the occurrence anddevelopment of colorectal polyps.