[Current update and testing procedures for genetic diagnosis in malignant neoplasm: additional information on pathological tests]. 
Targeted therapy refers to anticancer treatment which specifically targets key molecules of cancer cells.  The higher levels of expression of the epidermal growth factor receptor (EGFR) have also been shown to be correlated with non-small-cell lung cancer (NSCLC) and colorectal cancer (CRC).  Potential biomarkers should be investigated for the selection of patients with NSCLC most likely to benefit from epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), such as gefitinib.  Cetuximab is a monoclonal antibody that binds with high affinity to the EGFR, which is a prime target for new anticancer therapy.  However, the predictive value of EGFR expression and mutation of the K-ras gene has been assessed in response to cetuximab.  Many molecular techniques are available to assay for these biomarkers.  In this review, we present the current assessments of evidence for using these methods as biomarkers for molecular target-based therapy.