OBJECTIVETo investigate the feasibility of real-time PCR-optimized oligonucleotide probe method for detection of KRAS mutations in lung and colorectal carcinomas, as compared with Sanger sequencing method.

METHODSGenomic DNA was extracted from formalin fixed paraffin embedded samples of 221 lung carcinomas and 131 colorectal carcinomas after tumor cell content assessment and macrodissection. Real-time PCR-optimized oligonucleotide probe method and Sanger sequencing were performed to detect KRAS gene mutations. The frequency of KRAS mutation, mutation types, and their concordance were analyzed.

RESULTSKRAS mutation was detected in 6.3% (14/221) and 4.5% (10/221) of 221 lung cancer samples by using real-time PCR-optimized oligonucleotide probe method and Sanger sequencing, respectively, while in 41.2% (54/131) and 40.5% (53/131) of 131 colorectal cancer samples, respectively. There was no significant correlation between KRAS gene mutations and patients' gender and age (P > 0.05). The positive rate of KRAS codon 12 mutation was significantly higher than that of KRAS codon 13 mutation (P < 0.05). The overall concordance between real-time PCR-optimized oligonucleotide probe method and Sanger sequencing for KRAS mutation detection was 97.4%.

CONCLUSIONReal-time PCR-optimized oligonucleotide probe method provides an alternative method with high consistency and sensitivity as compared to Sanger sequencing in gene mutation detection.