The test must be conducted on the tumour tissue. Tumour tissue removed from the body (following biopsy or surgery) is processed into a tissue block and stored at the hospital where the operation takes place. Once a decision is made to test for KRAS mutations, the patient's doctor will arrange to have a portion of that saved tissue block sent to a laboratory where KRAS testing is conducted. Results are then sent back to the treating physician. The testing process may take up to 2-3 weeks.

Pivotal studies indicate a role of excision repair cross-complementation 1 (ERCC1) gene and ribonucleotide reductase M1 (RRM1) gene in conferring a differential sensitivity to cytotoxic chemotherapy and epidermal growth factor receptor (EGFR) gene has been recently extensively investigated in non-small-cell lung cancer (NSCLC).

Activation of the phosphatidylinositol 3-kinase (PI3K)-AKT pathway, regulates many normal cellular processes which include cell proliferation, survival, and motility. For these same reasons, the PI3K pathway also plays an important oncogenic role in many cancer types. PI3K signaling pathways can be deregulated by a variety of mechanisms in human tumors.