Clinical Significance Of EGFR Expression And Detection Of K-ras Gene Mutation In Colorectal Cancer Patients

Objective:To detect the overexpression of epidermal growth factor receptor(EGFR) in colorectal cancer of China and to evaluate the relationship between EGFR expression with different clinicopathological factors and patients'prognosis. To investigate the K-ras gene mutation status and its clinical significance in colorectal cancer patients.Methods:Immunohistochemistry method was used to detect the expression of EGFR in 1100 tumor samples. The most common k-ras gene mutation locus including 12 and 13 codon of 280 cases were detected by real-time fluorescence quantitative PCR (qPCR) and direct sequencing respectively.Results:The rate of EGFR expression was 24.55% in 1100 cases.Males had significantly higher expression of EGFR compared with females(Hc=5.9091;P=0.015).â…£andâ…¢tumor samples had significantly higher expression of EGFR compared with others ( Hc=32.6849;P <0.0001).EGFR expression in patients with lymphatic metastasis and distant metastasis was significantly higher than that without lymphatic or distant metastasis(Hc=32.6849 and Hc=152.3555;P<0.0001).No relationship was found between EGFR expression with patients'age,primary tumor location,tumor degree of histological differentiation,and overall survival. By direct sequencing, the positive rate of K-ras gene mutation was 33.57% (94/280).91 cases with K-ras gene mutation were detected by qPCR in 94 patients which have been confirmed by direct sequencing (sensitivity 96.8%);Meanwhile, 184 cases was negative detected by qPCR in 186 patients which have been confirmed by direct sequencing (specificity 98.9%); Compliance rate was 98.2% between qPCR method and direct gene sequencing. K-ras gene mutation was associated with sex and age (all P<0.05), but not with tumor site, differentiation, depth of invasion, TNM stage, lymph node metastasis and distant metastasis (all P>0.05).Conclusion:The overpression of EGFR protein and a large proportion of k-ras gene mutation were existing in colorectal cancer patients. The detection of EGFR protein expression can be used as a reference to evaluate the malignant behavior.Although there was no significant correlation between K-ras gene mutation and biological behavior of colorectal cancer, but a higher proportion of gene mutation in more than 60 years old female. Compliance rate was 98.2% between qPCR method and direct gene sequencing.Direct sequencing and qPCR present a high consistent results in the detection of the K-ras gene mutation.therefore, qPCR may be used as a rapid,simple and accurate detection method for K-ras gene mutation in colorectal cancer patients.