Context: Mutation status of the KRAS gene identifies a distinct disease subtype of metastatic colorectal carcinoma that does not respond to antibody therapeutics targeting the epidermal growth factor receptor. This is currently the only validated marker in metastatic colorectal carcinoma with a clear implication in treatment selection. KRAS testing is widely accepted in clinical practice to guide metastatic colorectal carcinoma therapeutic decisions, and there are many commercially available platforms to perform the test.
Objective: To evaluate the critical role of pathologists in the full implementation of KRAS testing by optimizing tumor tissue collection and fixation procedures and by choosing testing technologies and reliable Clinical Laboratory Improvement Amendments of 1988-certified laboratories to perform the tests.
Data sources: Prospective clinical trials, retrospective studies, and quality assessment and survey reports were identified in the following databases: PubMed, American Society of Clinical Oncology Proceedings (American Society of Clinical Oncology Annual Meeting and Gastrointestinal Cancer Symposium) and European Society for Medical Oncology Proceedings (Annals of Oncology European Society for Medical Oncology Congress and Annals of Oncology World Congress on Gastrointestinal Cancers).
Conclusions: More bona fide standards are needed to address the variety of available test methods, which have different performance characteristics including speed, sensitivity to detect rare mutations, and technical requirements. Refined standards addressing timing of KRAS testing, laboratory performance and accuracy, quality assurance and control, proper tissue collection, and appropriate result reporting would also be greatly beneficial. Pathologists should be aware that the amount of information they need to manage will increase, because future trends and technological advances will enhance the predictive power of diagnostic tests or the scope of the biomarker panels tested routinely across tumor types.