Clinicopathologic characteristics of EGFR, KRAS, and ALK alterations in 6,595 lung cancers

BACKGROUND EGFR, KRAS, and ALK alterations are major genetic changes found in non-small cell lung cancers (NSCLCs). Testing advanced lung adenocarcinoma tumors for these three genes is now standard care. The purpose of this study was to investigate the clinicopathologic expression pattern of these three genes in East Asian NSCLC patients. PATIENTS AND METHODS We conducted a retrospective study of all patients tested for mutations of these three genes at a single institute in Korea between 2006 and 2014. Study data were extracted from electronic medical records. Univariate and multivariate logistic regression analyses were used to measure associations between clinicopathologic features and alterations of EGFR, KRAS, and ALK. RESULTS We detected 12 EGFR-mutated tumors with additional mutations in KRAS (N=6, 0.1%) or ALK (N=6, 0.1%). General clinicopathologic characteristics of tumors with EGFR, KRAS, or ALK mutations were similar to previous reports. Patients having EGFR L858R point mutations were older than patients having EGFR exon 19 deletions. EGFR G719X point mutations were more common in men and smokers than exon 19 deletions or L858R point mutations. Tumors having KRAS G12C mutations were less often of mucinous type than those with G12D or G12V, mutations. CONCLUSIONS This is the largest three gene molecular epidemiology study in East Asian NSCLC patients. Each genetic alteration was associated with distinct clinicopathologic characteristics. Furthermore, different age and sex are associated with different subtypes of EGFR and KRAS mutations.