title: A systematic review of the incidence and prevalence of cancer in multiple sclerosis.
abstract: BACKGROUND
  Studies of cancer incidence and prevalence in multiple sclerosis (MS) have produced conflicting results.
  
  
  OBJECTIVE
  To estimate the incidence and prevalence of cancer in persons with MS and review the quality of included studies.
  
  
  METHODS
  We searched the PUBMED, SCOPUS, Web of Knowledge, and EMBASE databases, conference proceedings, and reference lists of all articles retrieved. Abstracts were screened for relevance by two reviewers. Data from included articles were captured using a standardized form, and the abstraction was verified by a second reviewer. We assessed quality of the included studies. We quantitatively assessed studies using the I (2) statistic, and conducted meta-analyses for population-based studies.
  
  
  RESULTS
  We identified 38 studies. Estimates for incidence and prevalence varied substantially for most cancers. In population-based studies, cervical, breast, and digestive cancers had the highest incidence. The risk of meningiomas and urinary system cancers appeared higher than expected, while the risks of pancreatic, ovarian, prostate and testicular cancer were lower than expected.
  
  
  CONCLUSIONS
  The complexity of understanding cancer risk in MS is augmented by inconsistencies in study design, and the relative paucity of age, sex and ethnicity-specific risk estimates from which the strong impact of age on the incidence of cancers can be assessed.
authors.affiliation: Department of Internal Medicine, University of Manitoba, Winnipeg, Canada/Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada rmarrie@hsc.mb.ca.
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie
authors.affiliation: Department of Internal Medicine, University of Manitoba, Winnipeg, Canada.
authors.forename: Nadia
authors.initials: N
authors.lastname: Reider
authors.affiliation: Mellen Center for MS Treatment and Research, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Cohen
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern, Dallas, TX, USA.
authors.forename: Olaf
authors.initials: O
authors.lastname: Stuve
authors.affiliation: Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Trojano
authors.affiliation: Department of Neurology, Copenhagen University Hospital Rigshospitalet, Denmark.
authors.forename: Per Soelberg
authors.initials: PS
authors.lastname: Sorensen
authors.affiliation: Scientific and Clinical Review Associates, LLC, Salisbury, CT, USA.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Reingold
authors.affiliation: Department of Biostatistics, University of Alabama at Birmingham, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Cutter
mesh_terms: D015897:Comorbidity; D006801:Humans; D015994:Incidence; D009103:Multiple Sclerosis / Q000453:epidemiology*; D009369:Neoplasms / Q000453:epidemiology*; D015995:Prevalence
keywords: Multiple sclerosis; cancer; comorbidity; incidence; prevalence; systematic review