Erythrocyte Lewis (A+B-) host phenotype is a factor with familial clustering for increased risk of Helicobacter pylori-related non-cardiac gastric cancer

Background: The purpose of the present study was to test whether host erythrocyte Lewis phenotypes correlated with the risk of gastric cancers. Because of the association of gastric cancer with familial clustering, cancer relatives were investigated as to whether they had unique distribution of Lewis phenotypes. Methods: The study prospectively enrolled 74 Helicobacter pylori-positive gastric cancer patients and 100 H. pylori-positive duodenal ulcer patients to serve as non-cancer controls after panendoscopy. In addition, 433 family members from the 74 index cancer and 100 non-cancer control patients were enrolled. All enrolled cases were checked for their H. pylori status and erythrocyte Lewis phenotypes, defined as Le^a-b-, Le^a-b+, Le^a+b-, and Le^a+b+ subtypes by the anti-Le^a and anti-Le^b monoclonal antibodies. Results: These H. pylori-infected patients with gastric cancer had a higher rate of Le^a+b- phenotype and a lower rate of Le^a-b+ phenotype than the non-cancer duodenal ulcer controls (20.3% vs 9%; 51.4% vs 72%, P < 0.05). Among these H. pylori-infected patients, the risk of the patients with Le^a+b- phenotype having gastric cancer was 3.15-fold higher as compared with those with the Le^a-b+ phenotype (P = 0.02, 95% confidence interval: 1.26-7.87). The offspring and cousins of the cancer patients had a higher rate of Le ^a+b- phenotype as compared to either that of the spouses of cancer index patients or to that of the family members of the non-cancer control (P < 0.05). Conclusion: Le^a+b- phenotype of the H. pylori-infected host could be a risk factor (with familial clustering) for gastric carcinogenesis.