RESUMO
Objective To evaluate the significance of COLD-PCR in detecting KRAS mutation of pancreatic cancer and colorectal cancer patients. Methods First, set up COLD-PCR and compared the sensitivities of COLD-PCR/Sanger sequencing with PCR/Sanger sequencing using mixed cell lines ( KRAS wild-type cell line SW116 and KRAS mutant cell line SW480).Then, detected KRAS mutation of 20 formalin-fixed paraffin-embedded samples of pancreatic cancer and 39 formalin-fixed paraffin-embedded samples of colorectal cancer using PCR/Sanger sequencing and COLD-PCR/Sanger sequencing, respectively and compared the coincidence rate and consistency. Results The low detection limits of PCR/Sanger respectively. KRAS frequency detected by COLD-PCR/Sanger sequencing [75% (15/20)] in 20 cases of pancreatic cancer was higher than that detected by regular PCR/Sanger sequencing [40% ( 8/20 ) ,x2 =5.013, P < 0.05]. KRAS frequency detected by COLD-PCR/Sanger sequencing [44% (17/39)] in 39 cases of colorectal cancer was higher than that detected by regular PCR/Sanger sequencing [31% (12/39) ,x2 =1. 372, P = 0. 174]. The coincidence rate of these two methods was 0. 730 and the difference had no statistical significance. The coincidence rate of detecting KRAS mutation was 65% in pancreatic cancer and the results showed a good correlation between two methods and the two methods had bad agreement in diagnosis (Kappa = 0. 364, P < 0. 05 ). COLD-PCR/Sanger sequencing could detect more cases of KRAS mutations from pancreatic caner than regular PCR/Sanger sequencing. This was because there were many non-tumor cells in pancreatic tumor tissue and COLD-PCR/Sanger sequencing was more sensitive than regular PCR/Sanger sequencing. The coincidence rate of detecting KRAS mutations was 87% in colorectal cancer and the results were showed a good correlation between two methods and the two methods had substantical agreement in diagonsis ( Kappa = 0. 730, P < 0. 05 ) . Conclusion COLD-PCR/Sanger sequencing is highly sensitive to screen KRAS mutation in pancreatic cancer and colorectal cancer patients.