Anti-Parietal Cell Antibodies Show Differential Associations With Stomach Cancer by Site and Helicobacter pylori Status.

[BACKGROUND] Autoimmune gastritis poses a risk for stomach cancer. However, its role relative to Helicobacter pylori-associated gastritis is uncertain. We assessed whether the associations between anti-parietal cell antibody (APCA) seropositivity and the risk of stomach cancer and its anatomical subtypes were modified by H. pylori infection.

[MATERIALS AND METHODS] A total of 244 incident gastric adenocarcinoma cases were identified from the Melbourne Collaborative Cohort Study (N = 41,513) and matched with 448 cancer-free controls using incidence density sampling with age as the time scale, matching on sex, year of birth, and country of birth. IgG antibodies against parietal cells and H. pylori were analyzed using commercially available ELISA kits. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression.

[RESULTS] Seropositivity for APCA was 21% for controls and 24% for cases (28% cardia, 23% non-cardia), while seropositivity for H. pylori was 62% for controls and 76% for cases (55% cardia, 81% non-cardia). The following ORs were observed for total, cardia, and non-cardia cancers in relation to APCA seropositivity: 1.21 (95% CI: 0.84-1.76), 1.99 (0.84-4.73), and 1.09 (0.71-1.66), respectively. Stronger associations were observed for cardia cancer in H. pylori-seropositive individuals (ORs, 3.60 [95% CI: 1.07-12.12] vs. 0.93 [0.24-3.57] for H. pylori-seronegative individuals; p = 0.15) and for non-cardia cancer in H. pylori-seronegative individuals (ORs, 2.56 [1.02-6.40] vs. 0.93 [0.56-1.54] for H. pylori-seropositive individuals; p = 0.06).

[CONCLUSIONS] Our findings suggest a more complex association between autoimmune gastritis and the risk of stomach cancer. They also highlight the importance of early detection of autoimmune gastritis in stomach cancer prevention.