THE INFLAMMATORY MICROENVIRONMENT IN SCREEN-DETECTED PREMALIGANT ADENOMATOUS POLYPS: EARLY RESULTS FROM THE INTEGRATED TECHNOLOGIES FOR IMPROVED POLYP SURVEILLANCE (INCISE) PROJECT
Introduction Around 40% of patients who attend for colonoscopy following a positive stool screening test have adenomatous polyps. Identifying which patients have a higher propensity for malignant transformation is currently poorly understood. The aim of the present study was to assess whether the type and intensity of inflammatory infiltrate differs between high-grade (HGD) and low-grade dysplastic (LGD) screen detected adenomas. Methods A representative sample of 207 polyps from 134 individuals were included from a database of all patients with adenomas detected through the first round of the Scottish Bowel Screening Programme (SBoSP) in NHS GG&C (April 2009 to April 2011). Inflammatory cell phenotype infiltrate was assessed by immunohistochemistry for CD3+, CD8+, CD45+ and CD68+ in a semi-quantitative manner at 20x resolution. Immune-cell infiltrate was graded as absent, weak, moderate or strong. Patient and polyp characteristics and inflammatory infiltrate were then compared between HGD and LGD polyps. Results CD3+ infiltrate was significantly higher in HGD polyps compared to LGD polyps (74% vs 69%, p<0.05). CD8+ infiltrate was significantly higher in HGD polyps compared to LGD polyps (36% vs 13%, p<0.001) where as CD45+ infiltrate was not significantly different (69% vs 64%, p=0.401). There was no significant difference in CD68+ infiltrate (p=0.540) or total inflammatory cell infiltrate (calculated from CD3+ and CD68+) (p=0.226). Conclusions This study reports an increase in CD3+ and CD8+ infiltrate with progression from LGD to HGD in colonic adenomas. It may therefore have a use in the prognostic stratification and treatment of dysplastic polyps.