Detection of Epidermal Growth Factor Receptor Mutations in Lung Adenocarcinoma: Comparing Cobas 4800 EGFR Assay With Sanger Bidirectional Sequencing

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Abstract

Micro-Abstract

We compared the performance of the Cobas 4800 assay against Sanger sequencing in the detection of epidermal growth factor receptor mutations in 474 samples. Excellent agreement was found between the 2 methods at 98.9%. The Cobas assay is a fast and diagnostically robust platform, only limited by its detection range. In contrast, Sanger sequencing has a lower analytical sensitivity. Ultimately, the use of a dual testing strategy is justified.

Introduction:

Accurate detection of epidermal growth factor receptor (EGFR) mutations has a crucial role in the current treatment of patients with lung adenocarcinoma, and identification of clinically relevant mutations would qualify patients for treatment with tyrosine kinase inhibitors. Historically, Sanger sequencing has been used as the reference standard assay for EGFR mutational analysis; however, Cobas 4800 is a relatively new method. In the present study, we compared the performance of the Cobas assay against that of Sanger sequencing.

Materials and Methods:

A total of 493 consecutive formalin-fixed paraffin-embedded samples of lung adenocarcinoma were simultaneously tested for EGFR mutations using both methods.

Results:

After exclusion of the invalid results (n = 19), 474 samples from 455 patients were analyzed. The Cobas assay showed a mutation detection rate comparable to that of Sanger sequencing (18.1% vs. 17.9%, respectively; P < .05). Excellent agreement of 98.9% (κ, 0.964) was observed between the 2 methods.

Conclusion:

The Cobas assay is a fast and diagnostically robust platform with high analytical sensitivity; however, it is limited by its detection range and low tolerance to low DNA quality. Sanger sequencing is mostly affected by its lower analytic sensitivity. Ultimately, a dual testing strategy will be justified to increase the detection of novel mutations and reduce the false-negative results within an acceptable turnaround time.

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