Small-scale external quality assessment of methylated and detection in China: findings from 2023-2024.

[OBJECTIVES] DNA methylation in short homeobox gene 2 () and RAS association domain family protein 1 () shows significant auxiliary diagnostic value for early-stage lung cancer. However, the detection accuracy is frequently compromised because of the complexity of the analytical procedures. This pilot external quality assessment (EQA) study evaluated the performance of methylated () and methylated () detection across clinical laboratories in China.

[METHODS] A sample panel was prepared containing two -positive samples, one -positive sample, one and double-positive sample, and one negative sample. The panel was randomly coded and distributed to clinical laboratories for and detection in 2023 and 2024. The returned results were compared and scored to evaluate laboratory performance.

[RESULTS] The sample panel demonstrated sufficient stability and applicability. Results were collected from 21 laboratories in 2023 and 29 laboratories in 2024. Approximately 90.5 % (19/21) and 75.9 % (22/29) laboratories achieved correct results in 2023 and 2024, respectively. Out of the 105 results in 2023 and 145 results in 2024, 1 false negative and 3 false positives were observed in 2023 and 6 false negatives and 12 false positives in 2024.

[CONCLUSIONS] This two-round EQA study in China emphasizes the need for improvement in the performance of and methylation detection. These results underscore the critical role of EQA schemes in monitoring and improving the detection quality in clinical laboratories. To address the challenges in and detection, targeted recommendations are proposed to enhance detection accuracy and reliability.