Association of gastric adenocarcinoma with the HLA class II gene DQB1*0301

Background and Aims: The HLA class II gene DQB1*0301 has been linked to several cancers. This study was designed to determine if HLA-DQB1*0301 is present at altered frequency in patients with gastric, colorectal, or pancreatic adenocarcinoma. Methods: Oligotyping for HLA-DQB1*0301 was performed for 159 Caucasian patients with 160 gastrointestinal adenocarcinomas (52 gastric, 62 colorectal, and 46 pancreatic adenocarcinomas) and compared with 200 Caucasian noncancer controls. Patients with gastric adenocarcinoma underwent extended HLA class II region oligotyping. Immunoglobulin G to Helicobacter pylori was detected by enzyme- linked immunosorbent assay. Results: HLA-DQB1*0301 was more common in patients with gastric adenocarcinoma than controls (54% vs. 27%; Bonferroni- corrected χ² p = 0.003; odds ratio, 3.2). HLA-DQB1*0301 was not associated with colorectal on pancreatic adenocarcinoma. No other HL4-DQB1 allele and no HLA-DQA1 or transporter associated with antigen processing 2 (TAP2) allele were present at altered frequency in patients with gastric adenocarcinoma. Serological evidence for H. pylori infection was less frequent in HLA- DQB1*0301-positive patients with gastric adenocarcinoma compared with HLA- DQB1*0301-negative patients (52% vs. 88%; Fisher's Exact Test; P = 0.007). Conclusions: HLA-DQB1*0301 is more common in Caucasian patients with gastric adenocarcinoma than noncancer controls. The mechanism linking HLA-DQB1*0301 with gastric adenocarcinoma is not likely through increased susceptiblity to H. pylori infection.