Neoplasms arising in large gastric hyperplastic polyps: endoscopic and pathologic features

Background Little is known about gastric neoplasms arising from hyperplastic polyps (HPs). Objective To investigate the risk factors associated with neoplasms within HPs and to evaluate the role of alterations of the p16-cyclin D1-pRb pathway in the malignant transformation of HPs. Design Retrospective, case-control study. Setting Tertiary-care center. Patients Between May 1995 and January 2011, a total of 809 HPs >1 cm were investigated. Associated neoplasms were present in 30 HPs (case group); 30 HPs without neoplasms were selected as a control group. Interventions Gastric polypectomy. Main Outcome Measurements The risk factors associated with neoplasms within HPs and immunohistochemical expression of p16, cyclin D1, p53, and Ki-67 between case and control groups. Results Of the 809 HPs, 15 had associated dysplasia, and 15 had carcinoma. Multivariate analysis showed that neoplasm was associated with patient age (odds ratio [OR] 1.159; 95% confidence interval [CI], 1.243-2.044; P < .001), polyp size (OR 1.103; 95% CI, 1.055-1.152; P < .001), and polyp lobulation (OR 4.549; 95% CI, 1.759-11.0766; P < .001) but not with location, multiplicity, intestinal metaplasia, growth pattern, or Helicobacter pylori infection. Loss of p16 expression and high Ki-67 expression were observed in dysplastic areas of HPs compared with the control group (p16 = 14.3% vs 60%; P = .001, Ki-67 = 60.7% vs 36.7%; P < .001). However, no significant differences were found in nondysplastic areas in both groups. Limitations Single-center, retrospective study. Conclusion HPs >1 cm may indicate the presence of neoplasms. Loss of p16 and high Ki-67 expression may be markers of HP-associated dysplasia.