Clonal evolution of colorectal cancer in a patient with serially resected metastases and liquid biopsies: a case report and discussion of the literature

BACKGROUND: Metastatic colorectal cancer represents a striking example of clonal heterogeneity and tumour evolution, which generates acquired resistance to therapy. Once hard to perform, the study of clonal heterogeneity is now significantly aided by the use of liquid biopsies. METHOD: We herein report a case of a patient with colorectal cancer and serial development of multiple metastases which were all resected and genotyped. A rare point mutation was identified in the primary tumour (but not in any of the organ metastatic sites), as well as in the first and the last out of three consecutive liquid biopsies. The review of the literature offered some insight in the evolution of the patient’s tumour and general directions on how to interpret liquid biopsy results. CONCLUSIONS: This patient case emphasises the need for large prospective studies designed to bridge liquid biopsy data with useful clinical endpoints, in order to optimally integrate this revolutionary tool in everyday practice.