Characteristics of tumor thrombosis in the inferior mesenteric vein from colorectal cancer: A report of three cases and review of the literature

INTRODUCTION: Intravenous tumor thrombosis is a rare condition in colorectal cancer and shows a locally aggressive biological behavior. We herein report three cases of colorectal cancer with tumor thrombosis in the inferior mesenteric vein (IMV) treated by colorectal resection combined with resection of the IMV under laparoscopic surgery. CASE PRESENTATION: In these three colorectal cancer patients with IMV tumor thrombus, IMV tumor thrombus was detected in all instances on preoperative computed tomography. Preoperative chemotherapy was also performed in one patient with concurrent liver metastasis. All patients underwent laparoscopic locally R0 resection; however, the pathological findings showed a positive margin for IMV resection in all patients. CLINICAL DISCUSSION: We reviewed 19 previously reported cases along with our 3 present cases and clarified the characteristics of colorectal cancer accompanied by IMV tumor thrombosis. IMV tumor thrombosis may be a risk factor for liver metastasis and R1 resection, and systemic treatment, including neoadjuvant chemotherapy (NAC), may be quite important. CONCLUSION: IMV tumor thrombosis may have a tendency to cause hematogenous metastasis. Systemic therapy, including NAC, may be useful, but since this is a rare condition, the accumulation of further cases is needed.