EGFR mutational analysis by Real-Time PCR
Approximately 10% of patients with NSCLC in the US and 35% in East Asia have tumor associated EGFR mutations. These mutations occur within EGFR exons 18–21, which encodes a portion of the EGFR kinase domain (Figure 1). EGFR mutations are usually heterozygous, with the mutant allele also showing gene amplification. Approximately 90% of these mutations are exon 19 deletions or exon 21 L858R point mutations. These mutations increase the kinase activity of EGFR, leading to hyperactivation of downstream pro-survival signaling pathways.
Regardless of ethnicity, EGFR mutations are more often found in tumors from female never smokers (defined as less than 100 cigarettes in a patient's lifetime) with adenocarcinoma histology. However, EGFR mutations can also be found in other subsets of NSCLC, including in former and current smokers as well as in other histologies.
In the vast majority of cases, EGFR mutations are non-overlapping with other oncogenic mutations found in NSCLC (e.g., KRAS mutations, ALK rearrangements, etc.).
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