title: Cancer Risk After Pernicious Anemia in the US Elderly Population.
abstract: OBJECTIVE
  Pernicious anemia, a result of autoimmune gastritis, is the most common cause of vitamin B12 deficiency, affecting 2% to 5% of the elderly population. Treatment with vitamin B12 cures the anemia, but not the gastritis. Findings from small studies have indicated that patients with pernicious anemia could have an increased risk of cancer.
  
  
  METHODS
  We performed a population-based, case-control study of individuals in the Surveillance, Epidemiology, and End Results-Medicare database, comparing 1,138,390 cancer cases (age, 66-99 y) with 100,000 matched individuals without cancer (controls). Individuals with pernicious anemia were identified based on their medical claims within the year before selection for the study. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression, and models were adjusted for sex, age, and calendar year of diagnosis and selection.
  
  
  RESULTS
  Compared with controls, we found individuals with pernicious anemia to be at increased risk for noncardia gastric adenocarcinoma (OR, 2.18; 95% CI, 1.94-2.45) and gastric carcinoid tumors (OR, 11.43; 95% CI, 8.90-14.69). In addition, people with pernicious anemia have an increased risk of developing tonsilar cancer (OR, 2.00; 95% CI, 1.40-2.85), hypopharyngeal cancer (OR, 1.92; 95% CI, 1.35-2.73), esophageal squamous cell carcinoma (OR, 2.12; 95% CI, 1.76-2.55), small intestinal cancer (OR, 1.63; 95% CI, 1.32-2.02), liver cancer (OR, 1.49; 95% CI, 1.28- 1.73), myeloma (OR, 1.55; 95% CI, 1.37-1.75), acute myeloid leukemia (OR, 1.68; 95% CI, 1.46-1.93), and myelodysplastic syndrome (OR, 2.87; 95% CI, 2.53-3.26). People with pernicious anemia have a lower risk of rectal cancer than the general population (OR, 0.82; 95% CI, 0.74- 0.92).
  
  
  CONCLUSIONS
  In a population-based, case-control study of individuals in the Surveillance, Epidemiology, and End Results-Medicare database, we found individuals with pernicious anemia to have significantly increased risks of gastric carcinoid tumors, adenocarcinomas, and other cancers located throughout the body.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland. Electronic address: murphygw@mail.nih.gov.
authors.forename: Gwen
authors.initials: G
authors.lastname: Murphy
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Sanford M
authors.initials: SM
authors.lastname: Dawsey
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Engels
authors.affiliation: Information Management Services, Inc, Calverton, Maryland.
authors.forename: Winnie
authors.initials: W
authors.lastname: Ricker
authors.affiliation: Information Management Services, Inc, Calverton, Maryland.
authors.forename: Ruth
authors.initials: R
authors.lastname: Parsons
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Arash
authors.initials: A
authors.lastname: Etemadi
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Shih-Wen
authors.initials: SW
authors.lastname: Lin
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Abnet
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Neal D
authors.initials: ND
authors.lastname: Freedman
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology*; D000368:Aged; D000369:Aged, 80 and over; D000752:Anemia, Pernicious / Q000150:complications*; D002276:Carcinoid Tumor / Q000453:epidemiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D018570:Risk Assessment; D013274:Stomach Neoplasms / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology
keywords: Acid Secretion; Chronic Atrophic Autoimmune Gastritis; Parietal Cells; Stomach Cancer