Rapid and Sensitive Detection of KRAS Mutation by Peptide Nucleic Acid-based Real-time PCR Clamping: A Comparison with Direct Sequencing between Fresh Tissue and Formalin-fixed and Paraffin Embedded Tissue of Colorectal Cancer

Colorectal cancer (CRC) is one of the most common malignancies and one of the leading causes of cancer-related death in the developed countries. Distant metastasis is the main cause of death in CRC patients. Surgical resection remains the potentially curative option for patients with metastatic CRC (mCRC). However, the prognosis is poor as the curative resection is possible in less than 25% of patients with stage IV disease, and less than 5% of patients with unresectable mCRC are alive after 5 years. Major efforts are being made to improve the prognosis for patients with mCRC, and especially to develop new therapeutic strategies. Monoclonal antibodies (mcAbs) (cetuximab and panitumumab) that target the epidermal growth factor receptor (EGFR) have recently been introduced for use as single agents or in combination with other chemotherapeutic drugs for the treatment of mCRC. However, the mcAbs only benefit a subset of cases that express the wild-type KRAS protein; tumors with mutated KRAS do not respond to this treatment modality. Thus, it is important that the KRAS mutation status be precisely determined to maximize the patient’s benefit in a clinical setting. While a variety of methods are available for the detection of KRAS mutations, nested polymerase chain reaction (PCR) followed by direct sequencing has been the gold standard to date. This method has two key disadvantages: its low sensitivity (2050%) and the important risk of contamination when handling the products of the PCR reaction. Thus, reliable and sensitive Rapid and Sensitive Detection of KRAS Mutation by Peptide Nucleic Acid-based Real-time PCR Clamping: A Comparison with Direct Sequencing between Fresh Tissue and Formalin-fixed and Paraffin Embedded Tissue of Colorectal Cancer