Reliability Assurance of Detection of EML4-ALK Rearrangement in Non-Small Cell Lung Cancer: The Results of Proficiency Testing in China.

INTRODUCTION: Currently, several approaches are being used to detect echinoderm microtubule associated protein like 4 gene (EML4)-anaplastic lymphoma receptor tyrosine kinase gene (ALK) rearrangement, but the performance of laboratories in China is unknown. To evaluate the proficiency of different laboratories in detecting EML4-ALK rearrangement, we organized a proficiency test (PT). METHODS: We prepared formalin-fixed, paraffin-embedded samples derived from the xenograft tumor tissue of three non-small cell lung cancer cell lines with different EML4-ALK rearrangements and used PTs to evaluate the detection performance of laboratories in China. RESULTS: We received results from 94 laboratories that used different methods. Of the participants, 75.53% correctly identified all samples in the PT panel. Among the errors made by participants, false-negative errors were likely to occur. According to the methodology applied, 82.86%, 76.67%, 77.78%, and 66.67% of laboratories using reverse transcriptase polymerase chain reaction, fluorescence in situ hybridization, next-generation sequencing, and immunohistochemical analysis, respectively, could analyze all the samples correctly. Moreover, we have found that the laboratories' genotyping capacity is high, especially for variant 3. CONCLUSION: Our PT survey revealed that the performance and methodological problems of laboratories must be addressed to further increase the reproducibility and accuracy of detection of EML4-ALK rearrangement to ensure reliable results for selection of appropriate patients.