Is Intraluminal Washout Necessary for Patients with Sigmoid Colon Cancer to Eliminate Exfoliated Cancer Cells as in Patients with Rectal Cancer? A Pilot Study at a Single Institute

OBJECTIVES: Rectal stump washout has been widely performed to prevent the implantation of exfoliated cancer cells (ECCs) in patients with rectal cancer. However, it remains unclear whether intraluminal washout before transection is required in patients with sigmoid colon cancer. Therefore, this pilot study was conducted to elucidate the necessity of intraluminal washout for sigmoid colon cancer patients in comparison with rectal cancer patients by cytological assessments. METHODS: A total of 16 patients with sigmoid colon cancer and 24 patients with rectal cancer who underwent sigmoidectomy or anterior resection with anastomosis using double-stapling technique were enrolled. A transanal washout sample was collected before washout and after irrigation with 500 and 1,000 mL of saline. Cytological assessments were conducted according to the Papanicolaou classification, and class IV and V cells were defined as malignant. RESULTS: Before washout, exfoliated cancer cells were found in 15 of 24 (62.5%) patients with rectal cancer and in 1 of 16 (6.2%) patients with sigmoid colon cancer (p < 0.001). Distal-free margin from the tumor was significantly shorter in patients with cancer cells (p = 0.002), and the length of the distal-free margin was significantly associated with the tumor location. After irrigation with 500 and 1,000 mL of saline, no cancer cell was found in all patients with sigmoid colon cancer, whereas ECCs were still found in five patients with rectal cancer (20.8%). CONCLUSIONS: Intraluminal washout with 1,000 mL may be sufficient for sigmoid colon cancer patients with longer distal-free margin. A large-scale, randomized controlled study is necessary to confirm these results.