Ultra-Rapid EGFR Testing in Non-Small Cell Lung Carcinoma Patients: Findings from a Canadian Clinical Testing Workflow.

Abstract

Single versus multigene molecular testing modalities for lung cancer offer distinct advantages and risks. We examined lung cancer cases with clinically requested ultra-rapid EGFR testing to (i) identify clinical features of rapid tested cases and their association with EGFR mutations, (ii) evaluate performance of single and multigene panel testing for ultra-rapid tested patients; and (iii) estimate laboratory costs and clinical outcomes. We include all retrospectively identified lung cancer patients who had ultra-rapid Idylla EGFR testing during the study period. Demographic data were retrieved from clinical charts and cost estimates were obtained from the BC Cancer Genetics and Genomics Laboratory. Of the 109 ultra-rapid tests, 94 (86%) were technically successful, yielding a positive or negative result. Of these, 62 tests (66%) identified an EGFR mutation. Patients with negative or failed testing were offered panel sequencing (n=47, 43%). Ultra-rapid testing had a median 1-day turnaround time and 95% sensitivity for EGFR mutation detection relative to panel sequencing. East/Southeast Asian ethnicity and female sex were significantly associated with EGFR mutation positivity in a multivariate logistic regression model (P=0.0001 and 0.029, respectively). The mean molecular testing cost per ultra-rapid tested patient, including panel sequencing for cases with negative/failed rapid tests, was $550.53 (standard deviation $284), slightly less than the $571 cost for panel sequencing. Single gene testing of patients with urgent clinical need or high probability of mutation may allow rapid time to treatment at similar testing costs.