The mutation rates of EGFR in non-small cell lung cancer and KRAS in colorectal cancer of Chinese patients as detected by pyrosequencing using a novel dispensation order

Abstract

Background: The purpose of this study was to develop a cost-effective approach for the determination of EGFR and KRAS mutations in formalin-fixed paraffin-embedded (FFPE) non-small cell lung cancer (NSCLC) and colorectal cancer (CRC) samples from Chinese patients based on a sensitive pyrosequencing (PS) technique. Methods: The NSCLC and CRC cell lines were tested to determine the limitation of detection and reproducibility of the PS method. In addition, 494 NSCLC and 1099 CRC patient samples were assayed by PS to evaluate the EGFR or KRAS mutation patterns according to the clinicopathological features. Results: The PS assay was able to reproducibly detect as few as 2 % mutant alleles with excellent linearity. EGFR mutations were detected in 35.63 % of the NSCLC samples, and KRAS mutations were detected in 39.76 % of the CRC samples. EGFR mutations were more frequently observed to be significant by multivariate analysis in NSCLC patients who were 65 years old or younger (OR = 2.51), had a nonsmoking history (OR = 3.63), and adenocarcinoma (OR = 3.57), but not in females (OR = 0.64). KRAS mutations were more frequently detected in CRC patients who were female (OR = 1.64) and 50 years old or older (OR = 4.17), and had adenocarcinoma (OR = 2.41). Conclusions: This is the first extensive validation of PS on FFPE samples using the detection of EGFR exons 18-21 mutations and KRAS exon 2 mutations. Our results demonstrate the utility of PS analysis for the detection of somatic EGFR and KRAS mutations in clinical samples and provide important clinical and molecular characteristics of NSCLC and CRC from Chinese patients.