ESR1 and melanoma: Furthermore, the results showed that ctDNA captures tumor heterogeneity by sharing 22 variants between melanoma (primary tumor) and liver (metastatic) and 12 additional variants that are unique to a tumor site, as well as being able to identify more frequently mutated genes concordant between WES ctDNA and tissue for breast cancer such as ESR1, KRAS, PIK3CA, PIK3R1, FAT1 and MED12, for gastrointestinal cancer APC, CASP8, GRIN2A, MYH9, TP53, ASXL1, CDH11 and KRAS; and melanoma PSIP1, RSPO2 and SF3B1 (Leenanitikul et al., 2023).