Plasma cell free DNA for EGFR mutation testing

Dear all,

I am writing to seek your advice and comments on the “system” used for liquid biopsy for EGFR mutation testing.

EGFR mutation testing can be done in tissue sample and also in plasma cell free RNA samples, namely liquid biopsy. Generally, molecular analysis of 3 main target mutation variants, T790M, L858R and EFGR Exon 19 deletion, would be done for patients with non-small cell lung carcinoma that have been given targeted therapy but developed relapse.

Take T790M mutation as an example, it was found that there are 2 relevant results, 55769-4 and 85838-8. May I know if I can directly adopt 55769-4 for Plasma cell free DNA for EGFR mutation testing or I should create a local extension by making reference to 85383-8 by using Plas.cfDNA as system please?

Thank you very much for your kind attention.