Gastric cancer is one of the most common cancers worldwide, with a high mortality
rate. The potential etiological role of autoimmune (AI) disorders has been described
in gastric cancer; however, the literature is controversial. This study aims to provide
a comprehensive summary of the association between autoimmune disorders and the incidence
of gastric cancer.This study was registered on PROSPERO under registration number
CRD42021262875. The systematic literature search was conducted in four scientific
databases up to May 17, 2021. Studies that reported standardized incidence rate (SIR)
of gastric cancer in autoimmune disorders were eligible. We calculated pooled SIRs
with 95% confidence intervals (CIs) in this meta-analysis.We included 43 articles
describing 36 AI disorders with data of 499,427 patients from four continents in our
systematic review and meta-analysis. Significantly increased incidence of gastric
cancer was observed in dermatomyositis (SIR = 3.71; CI: 2.04, 6.75), pernicious anemia
(SIR = 3.28; CI: 2.71, 3.96), inflammatory myopathies (SIR = 2.68; CI:1.40; 5.12),
systemic lupus erythematosus (SIR = 1.48; CI: 1.09, 2.01), diabetes mellitus type
I (SIR = 1.29; CI:1.14, 1,47), and Graves' disease (SIR = 1.28; CI: 1.16, 1.41). No
significant associations could be found regarding other AI disorders.Pernicious anemia,
Graves' disease, dermatomyositis, diabetes mellitus type I, inflammatory myopathies,
and systemic lupus erythematosus are associated with higher incidence rates of gastric
cancer. Therefore, close gastroenterological follow-up or routinely performed gastroscopy
and application of other diagnostic measures may be cost-effective and clinically
helpful for patients diagnosed with these autoimmune diseases.
