Purpose: K-ras mutations were reported to be in 40% -60% of patients with sporadic colorectal cancers (CRCs). HER-2/neu oncogene that is important in breast carcinoma was reported in CRCs in several studies. The aims of our study are to determine; the frequency of K-ras mutation in CRC and positivity of HER-2/neu, the relation between K-ras mutation and HER-2/neu positivity, and also the relation between clinicopathological findings with K-ras mutation and HER-2/neu expression. Methods: Total

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... 35 colon resection specimen from patients without distant metastasis who were operated due to colorectal adenocarcinoma were included in the study. The sections were examined with light microscopy. Vascular and perineural invasions and pericolonic tumor deposits (PCTD) were investigated. HER-2/neu was applied immunohistochemically. DNA sample obtained from tumor paraffin block was screened for presence of 20 mutations in K-ras gene-codon 12, 13, 61 by AutoGenomics and Infinity Analyzer. Results: K-ras gene mutation was detected in 14 of 35 patients (40%). HER-2/neu positivity was detected in 7 cases (28.57%). There was not any significant correlation between HER-2/neu positivity, K-ras gene mutation and clinicopathological findings. There was direct correlation between PCTD and vascular invasion. Conclusions: There was not correlation between K-ras mutation and clinicopathological findings similar to several other studies. The relation between HER-2/neu expression and clinicopathological findings was not found.