Abstract
Lung adenocarcinomas represents about 42% and 28% of NSCLC diagnosed in women and men. Several subtypes are recognized by WHO. EGFR, HER2 and KRAS gene mutations have been described.
Authors intends to identify differences between adenocarcinomas subtypes/patterns concerning EGFR, HER2 and KRAS mutations, gene copy number and protein expression.
45 lung adenocarcinomas were evaluated for EGFR, HER2 and KRAS mutational status by PCR, fragment analysis and direct sequencing, EGFR and HER2 gene copy number by fluorescence in situ hybridization (FISH). EGFR and c-erbB-2 protein expression was evaluated by immunohistochemistry (IHC).
8 cases showed EGFR exon 21 mutation (38,75%). In two cases the mutation was present in only one pattern of the tumour. 10 cases showed EGFR exon 19 deletions (32%), one case with the mutation present in only one of the patterns. 4 cases showed synchronous exon 19 deletions and exon 21 point mutations. Of the 14 cases with EGFR mutations 10 cases were FISH positive (71%). KRAS mutations were identified in 5 cases (16%), one coexisting with EGFR exon 21 point mutation. All cases were HER2 wild-type. 8 cases with EGFR mutations demonstrated EGFR protein expression and 6 cases were negative.
EGFR mutational status and FISH results showed a moderate agreement/concordance. Concordance between EGFR FISH results and mutational status with EGFR IHC expression was fair.
Frequently, when a mutation is identified it is present in all the patterns of 1 adenocarcinoma. Mutations of HER2 do not seem to be important in lung adenocarcinomas pathology. KRAS and EGFR mutations are in general mutually exclusive, but in rare cases they may coexist.
- © 2011 ERS
