title: Cancer in first-degree relatives of people with celiac disease.
abstract: BACKGROUND
  Celiac disease (CD) has been linked to cancer, especially lymphoproliferative malignancy (LPM). Earlier research has shown that first-degree relatives (FDRs) to individuals with CD are at increased risk of autoimmunity including CD, but data on their risk of cancer are scarce and contradictory. We aimed to assess whether Swedish FDRs to individuals with CD are at increased risk of cancer.
  
  
  METHODS
  Individuals with CD (identified through biopsy reports equal to Marsh grade III) were matched on sex, age, county, and calendar year with up to 5 control individuals. All FDRs (father, mother, sibling, offspring) of CD individuals ("celiac FDRs": n = 109,391) and controls (n = 548,465) were identified through Swedish healthcare registries. Through Cox regression, we calculated hazard ratios (HRs) for cancer incidence (all cancer, breast cancer, gastrointestinal cancer, and LPM).
  
  
  RESULTS
  During follow-up, celiac FDRs experienced 10,750 unique cancers as opposed to 54,686 in-control FDRs. Celiac FDRs were at a slightly lower risk of any cancer (HR 0.97, 95% confidence interval [CI] 0.95-0.99), partially due to the lower risk of breast cancer (HR 0.92, 95% CI 0.87-0.98). The relative risks of LPM (HR 0.99, 95% CI 0.91-1.08) and gastrointestinal cancer (HR 0.98, 95%CI 0.93-1.03) were both close to 1. As opposed to earlier research, we found no excess risk of LPM in siblings to individuals with CD (HR 0.98, 95% CI 0.81-1.19).
  
  
  CONCLUSIONS
  Celiac FDRs are not at increased risk of cancer, including LPM, arguing that shared genetics is unlikely to explain previous reports of an excess risk of LPM in patients with CD.
authors: Department of Health Management and Health Economy, Institute of Health and Society, University of Oslo, Norway Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA Primary care research unit, Vårdcentralen Värmlands Nysäter, Värmland County, Sweden Division of Gastroenterology and Hepatology, Department of Immunology, Mayo Clinic, Rochester, MN Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Stockholm Department of Pediatrics, Örebro University Hospital, Örebro, Sweden Division of Epidemiology and Public Health, School of Medicine, University of Nottingham, Clinical Sciences Building 2, City Hospital, Nottingham, UK Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY.
authors: Louise
authors: L
authors: Emilsson
authors: Joseph A
authors: JA
authors: Murray
authors: Daniel A
authors: DA
authors: Leffler
authors: Jonas F
authors: JF
authors: Ludvigsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002446:Celiac Disease / Q000235:genetics*; D002648:Child; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000235:genetics*; D016016:Proportional Hazards Models; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult