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Open Access Highly Accessed Technical advance

Fast simultaneous detection of K-RAS mutations in colorectal cancer

Ya-Sian Chang123, Kun-Tu Yeh4, Tien-Jye Chang3, Connie Chai1, Hsiu-Chin Lu1, Nicholas C Hsu1 and Jan-Gowth Chang156*

Author Affiliations

1 Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

2 Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

3 Department of Veterinary Medicine, National Chung Hsiung University, Taichung, Taiwan

4 Department of Pathology, Changhua Christian Hospital, Changhua, Taiwan

5 Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

6 Center for Excellence in Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

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BMC Cancer 2009, 9:179  doi:10.1186/1471-2407-9-179

Published: 11 June 2009

Abstract

Background

RAS genes acquire the most common somatic gain-of-function mutations in human cancer, and almost all of these mutations are located at codons 12, 13, 61, and 146.

Methods

We present a method for detecting these K-RAS hotspot mutations in 228 cases of colorectal cancer. The protocol is based on the multiplex amplification of exons 2, 3 and 4 in a single tube, followed by primer extension of the PCR products using various sizes of primers to detect base changes at codons 12, 13, 61 and 146. We compared the clinicopathological data of colorectal cancer patients with the K-RAS mutation status.

Results

K-RAS mutation occurred in 36% (83/228) of our colorectal cancer cases. Univariate analysis revealed a significant association between K-RAS mutation at codon 12 of exon 2 and poor 5-year survival (p = 0.023) and lymph node involvement (p = 0.048). Also, K-RAS mutation at codon 13 of exon 2 correlates with the size of the tumor (p = 0.03). Multivariate analysis adjusted for tumor size, histologic grade, and lymph node metastasis also indicated K-RAS mutations at codon 12 and 13 of exon 2 correlate significantly with overall survival (p = 0.002 and 0.025). No association was observed between codon 61 and 146 and clinicopathological features.

Conclusion

We demonstrated a simple and fast way to identify K-RAS mutation.