Patients who are treated for Helicobacter pylori infection and who take vitamin or garlic supplements may have reduced risk of death from gastric cancer, according to a recent study from China.
Researchers performed a blinded, randomized, placebo-controlled trial to determine whether treatment for H. pylori, vitamin supplements, or garlic supplements helped to prevent gastric cancer. Patients who lived in a region with high risk for gastric cancer were randomly assigned to H. pylori treatment, vitamin supplements, garlic supplements, or placebo. Those assigned to H. pylori treatment took two weeks of amoxicillin and omeprazole, while those assigned to vitamin or garlic supplements took vitamin C, E, and selenium or garlic extract and oil for 7.3 years, from 1995 to 2003.
The study's main outcome measures were cumulative incidence of gastric cancer, as determined through scheduled gastroscopies and active clinical follow-up, and death from gastric cancer, as determined from death certificates and hospital records. Secondary outcomes included associations with death from other types of cancer or from cardiovascular disease. Study results were published Sept. 11 by The BMJ.
Overall, 2,258 patients who were seropositive for H. pylori antibodies and 1,107 who were seronegative were randomly assigned to a treatment group. One hundred fifty-one incident gastric cancer cases and 94 deaths from gastric cancer were identified during clinical follow-up (1995 to 2017). Most cases of gastric cancer (79%) and most deaths (81%) occurred in patients who were positive for H. pylori at baseline. H. pylori treatment had a protective effect on gastric cancer incidence that persisted for 22 years after the intervention (odds ratio [OR], 0.48; 95% CI, 0.32 to 0.71). Vitamin supplementation also appeared to have a significant effect on gastric cancer incidence (OR, 0.64; 95% CI, 0.46 to 0.91), whereas garlic supplementation did not (OR, 0.81; 95% CI, 0.57 to 1.13).
For gastric cancer mortality, all three treatments were associated with significant reductions, with hazard ratios of 0.62 (95% CI, 0.39 to 0.99) for H. pylori treatment, 0.48 (95% CI, 0.31 to 0.75) for vitamin supplementation, and 0.66 (95% CI, 0.43 to 1.00) for garlic supplementation. H. pylori treatment's effects on gastric cancer incidence and mortality were noted early, at approximately eight years, as were vitamin supplementation's effects on mortality. The effects of vitamin supplementation on gastric cancer incidence and the effects of garlic supplementation were noted later. No statistically significant associations were seen between any of the interventions and the secondary outcomes.
The researchers noted that the numbers of events in their study were small, that they did not have information on patients' H. pylori infection status or other variables after the trial ended in 2003, and that their results may not be generalizable, among other limitations. They concluded that short-term H. pylori treatment was associated with long-term benefit for gastric cancer incidence and death and that multiyear vitamin supplementation was also associated with statistically significant reductions in both of these outcomes. Garlic supplementation, meanwhile, was associated with a statistically significant reduction in the latter outcome but not the former.
“These findings suggest many potential strategies for gastric cancer prevention,” the authors wrote. “However, before major public health campaigns for gastric cancer prevention are launched utilizing antibiotic based H pylori treatment or nutritional regimens, further large scale intervention trials are warranted to delineate the full range of beneficial and adverse effects of H pylori treatment, to confirm the preventive effects of vitamin and garlic supplementation, and to identify possible risks from nutritional regimens.”