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© 2009 American Academy of Neurology Cancer risk among patients with multiple sclerosis and their parentsFrom the Clinical Epidemiology Unit (S.B., S.M.M., A.E.) and Neuroimmunology Unit (T.O.), Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden; Faculty of Medicine (S.B.), Golestan University of Medical Sciences, Gorgan, Iran; Clinical Research Centre (S.M.M.), Örebro University Hospital, Örebro, Sweden; Department of Primary Care and Social Medicine (S.M.M.), Charing Cross Hospital, Imperial College, London, UK; and Division of Neurology (J.H.), Department of Clinical Neuroscience, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden. Address correspondence and reprint requests to Dr. Shahram Bahmanyar, Clinical Epidemiology Unit, Department of Medicine, Karolinska Institutet, Karolinska Hospital, SE-171 76 Stockholm, Sweden Shahram.Bahmanyar{at}ki.se Background: We investigated cancer risk among patients with multiple sclerosis (MS) and whether variation by age at MS diagnosis helps to elucidate mechanisms underlying the previously reported reduced cancer risk. We also studied cancer risk among parents to ascertain if MS susceptibility genes may confer protection against cancer in relatives. Methods: Cox proportional hazards regression, adjusted for age, sex, area, and socioeconomic index, estimated cancer risk among 20,276 patients with MS and 203,951 individuals without MS, using Swedish general population register data. Similar analyses were conducted among 11,284 fathers and 12,006 mothers of patients with MS, compared with 123,158 fathers and 129,409 mothers of controls. Results: With an average of 35 years of follow-up, there was a decreased overall cancer risk among patients with MS (hazard ratio = 0.91, 0.87–0.95). Increased risks were observed for brain tumors (1.44, 1.21–1.72) and urinary organ cancer (1.27, 1.05–1.53). Parents of patients with MS did not have a notably increased or decreased overall cancer risk. Conclusions: The reduction in cancer risk in patients with multiple sclerosis (MS) may result from behavioral change, treatment, or we speculate that some immunologic characteristics of MS disease activity improve antitumor surveillance. The lack of association among parents indicates that a simple inherited characteristic is unlikely to explain the reduced cancer risk among patients with MS. MS is associated with increased risk for some cancers, such as of urinary organs and brain tumors (although surveillance bias may be responsible).
Abbreviations: CI = confidence interval; HR = hazard ratio; MS = multiple sclerosis.
T.O. received grant support from the Bibbi and Nils Jensens Foundation, the Montel Williams Foundation, and the fp 6 of the EU NeuroproMiSe (LSHM-CT-2005-018637). S.M.M. received support from the Neurologiskt Handikappades Riskförbund. Disclosure: The authors report no disclosures. Received August 6, 2008. Accepted in final form January 16, 2009. This article has been cited by other articles:
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