Incidence of malignant neoplasms and mortality in people affected by multiple sclerosis in the epoch of disease-modifying treatments: a population-based study on Tuscan residents

Background Conflicting data are currently available on the risk of malignancies in people affected by multiple sclerosis (pwMS), and the potential relative contribution to this risk of disease-modifying therapies (DMTs) is still debated. Moreover, data on the long-term prognosis of pwMS mostly derive from natural history studies and updated observations during the treatment era are lacking. Methods Incidence of cancer and mortality were analysed in a pwMS cohort of residents of Tuscany over a 17-year period of observation during the treatment era and compared with the rates observed in a 1:10 sex- and age-matched control population resident in the same geographical area. Results Six-hundred and sixty-one pwMS were included; median age 43 years (range 19–80); 87% affected by relapsing-remitting MS. Sixty-eight percent of the cases were exposed to DMTs over the study period. Age and sex standardized incidence of malignancy did not differ between the groups: 3.9 × 1000 (95% confidence interval, CI, 3.75–4.15) person-years and 4.1 × 1000 (95% CI 3.76–4.42) person-years in the MS and control cohorts, respectively. The most frequent cancers reported in pwMS were breast, gastrointestinal and gynaecological cancers. Standardized mortality rates were 2.0 × 1000 person-years (95% CI 1.58–2.37) and 2.4 × 1000 (95% CI 2.03–2.78) person-years in the MS and control cohorts, respectively, and did not differ between groups, also after excluding traumatic cause-of-death (1.6 vs 1.7). Conclusions The incidence of cancer and mortality did not differ between pwMS and the general population residing in the same geographical area, suggesting that life expectancy of pwMS has improved over the treatment era.