CYP2E1 and adenoma: When the full-texts were reviewed, 63 studies were excluded for the following reasons: (i) they reported data on other CYP2E1 polymorphisms, were case-only studies, or did not contain useful information (N = 34); (ii) they were review articles (N = 23); (iii) the cases included patients with benign tumors such as adenomas (N = 3); (iv) they did not contain individual data for the rs3813867 and rs2031920 polymorphisms (N = 2); (v) study participants overlapped in more than one study (N = 1).