Affiliations: [a] Department of Medical Oncology, Cancer Institute/Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences; Beijing Key Laboratory of Clinical Study on Anticancer Molecular Targeted Drugs, Beijing, China | [b] Department of Pathology, Cancer Institute/Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
Correspondence:
[*]
Corresponding authors: Yuankai Shi, Department of Medical Oncology, Cancer Institute/Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences; Beijing Key Laboratory of Clinical Study on Anticancer Molecular Target Drugs, Beijing 100021, China. Tel.: +86 10 87788293; Fax: +86 10 87778740; E-mail: syuankaipumc@126.com; Xiaohong Han, Department of Medical Oncology, Cancer Institute/Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences; Beijing Key Laboratory of Clinical Study on Anticancer Molecular Target Drugs, Beijing 100021, China. Tel.: +86 10 87788701; Fax: +86 10 87778740; E-mail: xiaohonghan@hotmail.com.
Abstract: Background:The analysis of KRAS mutations in colorectal cancer (CRC) has made the need urgent for a reliable and easy to implement assay in daily practice. Objective:This study was designed to compare the different assays for KRAS testing and elucidate its mutation status in Chinese CRC patients. Methods:Direct sequencing was conducted to detect mutations in KRAS codons 12, 13 and 61 using 574 colorectal paraffin embedded clinical samples. And a subset of 66 samples was further detected independently by a commercial kit for comparison of different assays. Results:KRAS codons 12 and 13 mutations were detected in 40.9 and 42.4% of 66 CRC samples using the kit and direct sequencing methods, respectively. The concordance between two methods reached 95.5% (Kappa=0.907, P < 0.001). Workload and time to results were comparable for both. Moreover, KRAS mutations were detected in the total 574 CRC tumors by direct sequencing as followed: 25.3% in codon 12, 6.8% in codon 13, and 2.1% in codon 61. Notably, the mutations were more frequent in females than males, and patients older than 60 years exhibited higher rates of mutation (P < 0.05). Conclusions:Direct sequencing showed similar mutation rate as the detection kit and hence can be used effectively and reliably for clinical screening of somatic tumor gene mutations.
Keywords: Colorectal cancer, KRAS, mutation detection, direct sequencing
