The RAS Extended Plus test for colon cancer refers to a genetic test used to analyze specific mutations in the RAS gene family. The RAS genes (KRAS/Kirsten Rat Sarcoma Viral Oncogene Homolog, NRAS /neuroblastoma RAS viral oncogene homolog, and HRAS /Harvey rat sarcoma viral oncogene homolog) encode proteins involved in cell signaling pathways, controlling cell growth and division. Mutations in RAS genes are common in various cancers, including colorectal cancer. This test includes the analysis of all KRAS and NRAS mutations that are recommended as ‘RAS extended’ testing in international guidelines for targeted treatment of Colorectal cancers. In addition, the test also includes BRAF V600E mutation testing which is recommended for colorectal cancer prognostication, and evaluation of Lynch syndrome risk. Other genes tested in the panel are PIK3CA and PTEN for informational purposes.

Testing for these mutations is crucial for determining the appropriate treatment strategy, especially in the context of anti-Epidermal Growth Factor Receptor (EGFR) therapy. Mutations in the RAS genes, particularly in KRAS and NRAS, have been associated with resistance to anti-EGFR (Epidermal Growth Factor Receptor) therapies such as cetuximab and panitumumab. These targeted therapies are used in the treatment of metastatic colorectal cancer. Patients with RAS mutations may not respond well to these treatments.

The RAS Extended Plus test helps oncologists personalize treatment plans for patients with colorectal cancer. Knowing the RAS mutation status helps determine whether anti-EGFR therapy or alternative treatment options should be pursued.