Objective: We aimed to investigate whether the elevated risk of gastric cancer among patients with gastric ulcer (GU) and the enigmatic low risk among patients with duodenal ulcer (DU) pertain to both cardia and noncardia cancer. We also studied the risks among operated patients while taking the disparate baseline risks into consideration.
Methods: Retrospective cohorts of 59,550 and 79,412 unoperated patients with DU and GU, respectively, plus 12,840 patients with partial gastric resection and 8,105 with vagotomy, recorded in the Swedish Inpatient Register since 1970, were followed from the first hospitalization (date of operation for the surgery cohort) until occurrence of any cancer, death, emigration, definitive surgery, or December 31, 2003. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) expressed relative risk (RR), compared to the age-, sex-, and calendar period-matched Swedish population. Cox regression produced adjusted RR estimates among operated patients, relative to unoperated ones with the same ulcer type.
Results: While unoperated DU patients had a halved risk of noncardia cancer (SIR=0.5, 95% CI 0.4-0.7), their risk of cardia cancer was slightly above expectation (SIR=1.2, 95% CI 0.8-1.7). Unoperated GU patients had doubled risks for both cancers (SIR=2.1, 95% CI 2.0-2.4 and SIR=1.9, 95% CI 1.4-2.3, respectively). DU patients who underwent gastric resection had a 60% risk elevation (RR=1.6, 95% CI 1.0-2.5) compared to unoperated ones. Vagotomy was associated with a greater risk in the first 10 yr, but this excess disappeared with further follow-up. Resected GU patients had a 40% risk reduction relative to their unoperated peers (RR=0.6, 95% CI 0.5-0.8). This reduction persisted well beyond the first postoperative decade.
Conclusion: The DU-related protection against gastric cancer does not seem to pertain to cardia cancer. With gastric resection, risks are shifted toward normality, regardless of underlying ulcer type.