DPP4 and adenoma: Interestingly, these lesions, considered in literature as advanced adenomas due to their increased risk of transforming into cancer, displayed the most elevated mean levels of anti-CD26 IgA (0.32 ± 0.12 Abs), IgG (0.33 ± 0.06 Abs), and IgM (0.23 ± 0.13 Abs) (NCF+BP+HP vs. AA, Mann-Whitney U test p = 0.098, p = 0.030, and p = 0.143, respectively).