However, in this study, we focused on the most recurrent EGFR alterations, and found a strong correlation between the SQI value and VAF and SQI and the number of mutated copies/mL, indicating that the SQI accurately reflects the VAF kinetics in NSCLC patients harboring deletions in exon 19 in EGFR. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.