A 76-year-old woman was diagnosed with left-sided transverse colon cancer invading the pancreatic tail with multiple liver metastases and peritoneal dissemination. Preoperative diagnosis was cT4b(SI)N2aM1c(H3, P1), cStage Ⅳc, harboring BRAF V600E mutation. Transverse colostomy was performed, and FOLFOXIRI plus bevacizumab(BEV)was administered. After 12 chemotherapy cycles, the primary tumor and metastatic lesions showed partial response. Because of CEA elevating after 5-FU plus LV plus BEV as maintenance therapy was changed, the regimen was switched to encorafenib plus binimetinib plus cetuximab as the second-line chemotherapy. The patient developed dermatitis around the colostomy after the start of the second-line chemotherapy, resulting in temporally cetuximab monotherapy. After improvement of dermatitis, the patient resumed encorafenib plus binimetinib, improving liver metastases. Eight months after the start of the second- line, the patient has been administered with triple therapy and had stable disease status.