Diagnostic RAS mutation analysis by polymerase chain reaction (PCR)

• RAS mutation analysis is an important companion diagnostic test for colorectal cancer, in which extended RAS mutation testing incorporates codons 12 and 13 of exon 2; 59 and 61 of exon 3; and 117 and 146 of exon 4 of KRAS and NRAS.
• Other cancers contain RAS mutations, and knowledge of RAS mutation status can be helpful for lung cancer and melanoma patients.
• A range of widely validated commercially available PCR methods are available, as well as a laboratory developed tests.
• Most require DNA extraction by automated or manual methods.
• PCR methods have restricted coverage of mutation hotspots in comparison with targeted next generation sequencing.
• However, PCR methods are relatively simple to perform, and provide rapid inexpensive diagnosis with good sensitivity, providing an excellent option for clinical molecular pathology.

RAS mutation analysis is an important companion diagnostic test. Treatment of colorectal cancer with anti-Epidermal Growth Factor Receptor (EGFR) therapy requires demonstration of RAS mutation status (both KRAS and NRAS), and it is good practice to include BRAF. In Non-Small Cell Lung Cancer (NSCLC) and melanoma, assessment of RAS mutation status can be helpful in triaging patient samples for more extensive testing. This mini-review will discuss the role of PCR methods in providing rapid diagnostic information for cancer patients.