title: EGFR fluorescence in situ hybridization-positive lung adenocarcinoma: incidence of coexisting KRAS and BRAF mutations.
abstract: Despite growing evidence that epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation analysis is the most reliable predictor of the lung carcinoma response to EGFR-targeted therapies, there is still discussion about the role of EGFR fluorescence in situ hybridization (FISH). Studies focusing on EGFR FISH as a predictor of response to EGFR-targeted therapies mostly focused on the relationship between EGFR FISH and EGFR mutations. The incidence of KRAS and V-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutations in EGFR-amplified or EGFR FISH-positive lung adenocarcinomas remains unknown. The aim of this study was to prospectively characterize the incidence of KRAS and BRAF mutations in EGFR FISH-positive surgically treated lung adenocarcinomas. Of 386 primary lung adenocarcinomas, 77 (20%) were EGFR FISH positive by University of Colorado criteria. The incidence of KRAS mutations in EGFR FISH-positive lung adenocarcinomas was 23% and was not significantly different from the incidence of KRAS mutations in EGFR FISH-negative subsets of adenocarcinoma (32%). A higher mean ratio between EGFR and chromosome 7 enumeration probe (EGFR/CEP7) was observed in EGFR-mutated tumors when compared to cases with KRAS mutation (13 versus 4.5, respectively). Our results showed significant number of EGFR FISH positive/amplified lung adenocarcinomas harboring KRAS mutation. It appears that an increase in EGFR/CEP7 ratio to cutoff point of 4.5 may distinguish between coexisting EGFR (FISH ratio of >5) or KRAS (FISH ratio of 2 to 5) mutations. Observations presented here indicate that the patient selection for EGFR-targeted therapies should include EGFR and KRAS mutational analysis, probably complemented by EGFR FISH studies.
authors.affiliation: Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA. chioseasi@upmc.edu
authors.forename: Simion
authors.initials: S
authors.lastname: Chiosea
authors.forename: Yongli
authors.initials: Y
authors.lastname: Shuai
authors.forename: Kathleen
authors.initials: K
authors.lastname: Cieply
authors.forename: Marina N
authors.initials: MN
authors.lastname: Nikiforova
authors.forename: Sanja
authors.initials: S
authors.lastname: Dacic
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics / Q000648:ultrastructure; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011132:Polyribosomes / Q000235:genetics; D011446:Prospective Studies; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D066246:ErbB Receptors; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins