Cancer risk and mortality in multiple sclerosis: The need for vigilance

Abstract

Several investigators have addressed the possibility of a link between cancer and multiple sclerosis (MS). The consensus view favours an increased risk, but analysis is compromised by multiple confounders, including small sample sizes, age and socio-economic group of the population in question, level of education and whether a cancer diagnosis was based on the less reliable death certificates compared to cancer registries. Coupled with this is the problem of subsequent cancer-related mortality in those with MS compared to those without MS. Until 1996 patients were treated chiefly with steroids, azathioprine, cyclophosphamide and occasionally mitoxantrone. Each of these has its own potential long-term risk of cancer probably least of all with steroids. Mitoxantrone has a small but definite risk of acute myeloid leukaemia particularly if patients are exposed to more than 60mg/M2 ( Lebrun and Rocher, 2018 Lebrun C Rocher F. Cancer risk in patients with multiple sclerosis: potential impact of disease-modifying drugs. CNS drugs. 2018; 32 (Oct): 939-949 Google Scholar ). Azathioprine is connected with a particularly high rate of non-Hodgkin lymphoma in renal transplant cases ( Kinlen, 1992 Kinlen L. Immunosuppressive therapy and acquired immunological disorders. Cancer research. 1992; 52 (Oct 1): 5474s-5476s Google Scholar ) but this has not been found for large studies in MS that had a follow-up range of <10 years and a total dose exposure of no more than 600g ( Casetta et al., 2007 Casetta I Iuliano G Filippini G. Azathioprine for multiple sclerosis. Cochrane Database of Systematic Reviews. 2007; Google Scholar ).