title: Risk of non-Hodgkin's lymphoma in primary Sjögren's syndrome: a population-based study.
abstract: OBJECTIVE
  Primary Sjögren's syndrome (SS) is associated with an increased risk of non-Hodgkin's lymphoma (NHL), but the reported prevalence and risk vary considerably. The objective of this study was to determine the risk of NHL in a well-defined population-based primary SS cohort in Norway.
  
  
  METHODS
  The authors examined all patients fulfilling the American-European Consensus Group criteria for primary SS from 2 Norwegian counties and compared the data to the Cancer Registry of Norway to identify the primary SS patients who had lymphoma. In addition, lymphoma patient files from the same period were reviewed for undiagnosed primary SS to ensure the quality of registry data.
  
  
  RESULTS
  As of July 1, 2009, 443 living subjects with primary SS were identified in an area with 896,840 inhabitants, which is 18.6% of the total population of Norway. Seven cases of NHL (1.6%) were found during a total followup of 3,813 person-years, resulting in a standardized incidence ratio of 9.0 (95% confidence interval 7.1-26.3) for NHL in primary SS patients.
  
  
  CONCLUSIONS
  The risk of NHL in patients with primary SS in Norway is increased 9 times compared with the general population. This is in accordance with recent studies, and the quality and completeness of the registries and strict use of diagnostic criteria support the validity of the results.
authors.affiliation: Stavanger University Hospital, Stavanger, Norway. josj@sus.no
authors.forename: Svein J
authors.initials: SJ
authors.lastname: Johnsen
authors.forename: Johan G
authors.initials: JG
authors.lastname: Brun
authors.forename: Lasse G
authors.initials: LG
authors.lastname: Gøransson
authors.forename: Milada C
authors.initials: MC
authors.lastname: Småstuen
authors.forename: Tom B
authors.initials: TB
authors.lastname: Johannesen
authors.forename: Karstein
authors.initials: K
authors.lastname: Haldorsen
authors.forename: Erna
authors.initials: E
authors.lastname: Harboe
authors.forename: Roland
authors.initials: R
authors.lastname: Jonsson
authors.forename: Peter A
authors.initials: PA
authors.lastname: Meyer
authors.forename: Roald
authors.initials: R
authors.lastname: Omdal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods*; D012042:Registries; D012307:Risk Factors; D012859:Sjogren's Syndrome / Q000175:diagnosis* / Q000453:epidemiology*; D055815:Young Adult