However, in the cases of the new EGFR exon 19 deletion mutation and exon 20 insertion identified with very low abundance (0.26% for exon 19 deletion and 0.06%, and 0.04% for exon 20 insertion, respectively), this may represent an ongoing genetic evolution during the process of tumourogenesis in the cell clones of adjacent non-tumour tissue [42]. Here, EGFR is linked to neoplasm.