[Rectosigmoid Colon Cancer with Unresectable Liver Metastases That Responded Remarkably to Bevacizumab-Combined Chemotherapy-A Case Report].

A woman in her 50s was referred to our hospital after a health checkup revealed a large liver tumor on abdominal ultrasonography. Colonoscopy revealed a Type 3 lesion occupying half of the rectosigmoid colon, and a biopsy confirmed a diagnosis of well-differentiated tubular adenocarcinoma. Contrast-enhanced computed tomography revealed multiple liver metastases in both lobes, and laparoscopic high anterior resection was performed(pT3N0M1a, Stage Ⅳ). Post-operatively, chemotherapy was initiated with a single course of mFOLFOX6, followed by 11 courses of mFOLFOX6+bevacizumab. Due to worsening peripheral neuropathy, the regimen was switched to FOLFIRI+bevacizumab, which was administered over 43 courses. Although the liver metastases steadily reduced in size, the response remained as a partial response. Two years and 6 months after the initiation of chemotherapy, the patient elected to discontinue treatment, and follow-up observation was continued thereafter. Three years and 4 months after discontinuation of chemotherapy, the liver metastases continued to regress, suggesting a clinical complete response.