For example, in colorectal cancer patients undergoing anti‐EGFR treatment, detecting KRAS mutations in ctDNAs of patients with anti‐EGFR therapies can identify relapse10 months before radiographic documentation of disease progression.116 Similar situations also include BRAF L597 mutation in cutaneous melanoma with MEK inhibitor and PIK3CA mutation in solid tumours with PIK3CA inhibitors.117, 118. This evidence concerns the gene EGFR and cutaneous melanoma.