Long term follow-up of EGFR mutated NSCLC cases.

PURPOSE

A substantial fraction of all non-small cell lung cancers(NSCLC) carry a mutation in the EGFR gene for which an effective treatment with anti-tyrosine kinases(TKIs) is available. We studied the long term survival of these patients following the introduction of TKIs.

EXPERIMENTAL DESIGN

All consecutive cases of NSCLC newly diagnosed with advanced disease were referred for free tumor EGFR mutation testing at Clalit's national personalized medicine laboratory. Mutations and deletions in target codons 18-21 of EGFR were sought using RT-PCR and fragment analysis. Comprehensive EMRs were used to collect full data on treatments and clinical status.

RESULTS

A cohort of 3,062 advanced NSCLC cases, included 481(15.7%) somatic EGFR mutation carriers (17.5% of all adenocarcinomas, 26.7% of females with adenocarcinomas). TKIs treatment to EGFR mutation carriers was provided to 85% of all eligible. After a median follow up period of 15.9 months for EGFR mutated cases the hazard ratio for overall survival of EGFR-mutated NSCLC treated with TKIs was 0.55(0.49-0.63, p<0.0001) when compared with EGFR wild-type(WT) tumors under usual care. After adjusting for age, sex, ethnicity, smoking history and tumor histology, all of which had an independently significant effect on survival, the HR for TKI-treated, EGFR-mutated tumors, was 0.63 (0.55-0.71, p<0.0001). Treating EGFR-WT cases with TKIs yielded a high HR=1.32 (1.19-1.48).

CONCLUSIONS

TKIs given to EGFR mutated advanced NSCLC demonstrated a substantial survival benefit for at least five years. Squamous histology, smoking, male sex and Arab ethnicity were associated with higher NSCLC mortality hazard. Treating non-EGFR-mutated NSCLC with TKIs seems detrimental. Statement of Significance: • TKIs given to EGFR mutated advanced NSCLC demonstrated a substantial survival benefit for at least five years but not much longer. • Treating non-EGFR-mutated NSCLC with TKIs seems detrimental and should probably be avoided. • Squamous histology of non-small cell lung cancer, smoking history, male sex and Arab ethnicity were associated with altogether higher NSCLC mortality hazard.