Objective: Previous studies have indicated that EGFR exon 19 deletions in non-small cell lung cancer (NSCLC) are associated with better outcomes to tyrosine kinase inhibitors (TKIs) than the L858R mutation. This study aimed to evaluate whether T790M, a resistant mutation, is more likely to coexist with L858R mutation than with exon 19 deletions in pretreatment NSCLC patients.
Materials and method: We searched MEDLINE and EMBASE up to Nov 30th, 2015 to identify randomized controlled trials (RCTs) and observational studies that reported pretreatment T790M and EGFR-activating mutation. A meta-analysis was performed using a random-effects model. The primary outcome was odds ratio (OR) of pretreatment T790M mutation in NSCLC co-existing with L858R mutation and exon 19 deletions. Stratified analysis was performed based on sensitivity of mutation detection methods for T790M.
Results: We identified 15 observational studies and 3 RCTs for analysis. Pretreatment T790M was more frequent in L858R than in exon 19 mutated patients. The association of T790M and L858R was statistically significant in observational studies (OR, 1.65, 95% CI, 1.17-2.32), with less precision in RCTs (OR, 1.84, 95% CI, 0.96-3.52). In the stratified analysis based on the sensitivity of the mutation detection methods, the association was observed in the studies using intermediately (detection limit <5% and ≥ 0.1%; OR, 2.23, 95% CI, 1.19-4.17) and highly sensitive methods (detection limit <0.1%; OR, 1.74, 95% CI, 1.10-2.73), but not in those using low sensitivity methods (detection limit >5%; OR, 1.28, 95% CI, 0.74-2.23).
Conclusions: Pretreatment EGFR T790M mutation is more likely to coexist with L858R mutation than with exon 19 deletions in NSCLC. This association was observed only in studies using sensitive mutation detection methods (<5%).
Keywords: Epidermal growth factor receptor; Exon 19 deletions; L858R; Meta-analysis; Non-small cell lung cancer; T790M.
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