Results of the Dunnett test revealed that the BMI-1 gene was overexpressed in adenoma tissues by 1.042-fold (CI − 0.08533 to − 0.0003886, p = 0.04) and in papillary carcinoma tissues by 1.047-fold (CI − 0.09009 to − 0.005150, p: 0.02) compared with the adjacent healthy tissues. This evidence concerns the gene BMI1 and adenoma.