While the amplification refractory mutation system (ARMS) method has been used to detect EGFR mutations in both lung cancer tissues [13] and plasma ctDNA [14], a single allele base extension reaction combined with mass spectrometry (SABER/MassARRAY) has also been used to detect the T790M EGFR mutation in plasma ctDNA [15]. The gene discussed is EGFR; the disease is lung carcinoma.