An international team, from Sweden and the USA, tested the hypothesis that exposure to high doses of antibiotics reduces risk for gastric cancer via possible eradication of Helicobacter pylori.
A nationwide case-control study was conducted, nested in a cohort of 39,154 patients who underwent hip-replacement surgery between 1965 and 1983. These patients were monitored because they often receive prophylactic antibiotic treatment.
During follow-up through 1989, 189 incident cases of gastric cancer were identified. For each case, three controls were selected from the cohort.
Exposure data were abstracted from hospital records. Blood samples from a separate cohort undergoing hip-replacement surgery were analyzed for anti-Helicobacter pylori IgG, before and after surgery.
"Antibiotic treatment at a relatively advanced age reduces gastric cancer risk"
Dr Katja Akre
The team found that both long-term antibiotic treatment before surgery (odds ratio [OR] = 0.3) and prophylactic antibiotic treatment (OR = 0.7) conferred a reduction in gastric cancer risk.
The reduction appeared stronger after 5 years (OR = 0.6) than during shorter follow-up after hip replacement (OR = 0.8).
There was an apparent decrease in risk with increasing body-weight adjusted doses of antibiotics (P = 0.13). However, the rate of Helicobacter pylori antibody disappearance was not strikingly higher in the cohort of patients undergoing hip replacement than in a control cohort.
Dr Katja Akre said on behalf of the group, "Our findings provide indirect support for the hypothesis that treatment with antibiotics at a relatively advanced age reduces the risk of gastric cancer."