Clinical characteristics of sentinel polyps and their correlation with proximal colon cancer: A retrospective observational study

BACKGROUND: Colorectal cancer is a common malignant tumor of the digestive tract. The relationship between sentinel polyps (rectal polyps with proximal colon cancer) and proximal colon cancer has received extensive attention in recent years. However, there is still no clear conclusion regarding the relationship. AIM: To investigate the clinical characteristics of sentinel polyps and their correlation with proximal colon cancer. METHODS: A retrospective analysis of 2587 patients with rectal polyps from January 2006 to December 2017 was performed. According to whether or not proximal colon cancer was diagnosed, the patients were divided into either a sentinel polyp group (192 patients) or a pure rectal polyp group (2395 patients). The endoscopic features, clinicopathological features, therapeutic effects, and short-term prognosis were analyzed and compared between the two groups. RESULTS: The mean age of patients in the sentinel polyp group was generally higher than that of the pure rectal polyp group, and the positivity rates of anemia, stool occult blood, and tumor markers of the sentinel polyp group were also significantly higher than those in the rectal polyp group (χ(2) = 90.56, P < 0.01; χ(2) = 70.30, P < 0.01; χ(2) = 92.80, P < 0.01). The majority of the patients in the sentinel polyp group had multiple polyps, large polyps, adenomatous polyps, or sessile polyps (χ(2) = 195.96, P < 0.01; χ(2) = 460.46, P < 0.01; χ(2) = 94.69, P < 0.01; χ(2) = 48.01, P < 0.01). Most of the proximal colon cancers were Duke’s A and B stages in the sentinel polyp group. In the pure rectal polyp group, 2203 patients underwent endoscopic treatment, and all of the patients were cured and discharged. In the sentinel polyp group, 65 patients underwent radical operation, and 61 patients received endoscopic submucosal dissection or endoscopic mucosal resection. Additionally, 21 patients were lost to follow-up after 6-12 mo, and the loss rate was 10.94%. A total of 63.16% of patients experienced remission without tumor recurrence or metastasis, 33.33% of patients experienced tumors regression or improved symptoms, and the other 3.51% of the patients died. CONCLUSION: If there are multiple, sessile, and adenomatous rectal polyps with a maximum diameter > 1 cm, the possibility of the carcinogenesis of the polyps or of the proximal colon should be monitored closely. These patients should be followed in the short-term and should undergo a whole-colon examination.