In a prospective clinical study, Bai et al. showedthat peritoneal lavage CTCs and ctDNA can predict metachronous peritoneal metastases aftersurgery in patients with advanced GI cancer (47), while Jung et al. confirmed the utility of liquid biopsy for guiding therapy in HER2-positive metastatic GC (48). Here, ERBB2 is linked to gastric cancer.