Good response to leucovorin and fluorouracil plus oxaliplatin and cetuximab therapy in a patient with metastatic ascending colon cancer harboring a KRAS p.G13D mutation.

The effectiveness of cetuximab (Cmab) against KRAS p.G13D mutant-type tumors has been reported. In this study, we report a case of metastatic ascending colon cancer harboring a KRAS p.G13D mutation in a 65-year-old female. Considering the absence of symptoms and the post-operative risk of respiratory system complications due to multiple lung metastases, particularly at the entrance to the left main bronchus, anticancer drug therapy was selected as first-line therapy. With informed consent, FOLFOX4 [folinic acid (FOL), fluorouracil (F) plus oxaliplatin (OX)] + Cmab therapy was administered as preoperative chemotherapy. A good preoperative response was obtained to the chemotherapy, with a metastatic lesion disappearing from the entrance to the left main bronchus. Subsequent resection was performed successfully with no post-operative complications. Although a histopathological examination of the resected tissue specimen revealed residual cancer cells, it also showed the marked efficacy of the chemotherapy regimen used. In this study, we describe a case of metastatic ascending colon cancer harboring a KRAS p.G13D mutation in which the patient responded well to first-line therapy with FOLFOX4 + Cmab.