Patients with multiple sclerosis (MS) who have received immunosuppressant therapy (IS) face a greater risk for cancer than those who have not received IS therapy, according to results of an Italian cohort study published in BMC Neurology.
Cancer risk in 531 patients with MS (346 women, 185 men) who had undergone IS treatment (azathioprine, mitoxantrone, and/or cyclophosphamide) was compared with cancer risk in an equal number of patients with MS not exposed to IS therapy. Length and dose of exposure to IS treatment were used to calculate an individual’s relative cancer risk.
Demographic and clinical characteristics (age, disease duration, and cumulative length of follow-up) of the 2 groups of patients were similar. The mean follow-up period was 10 years for the entire cohort. Cancer incidence among individuals with MS and in the general population (those without MS) was also assessed to determine whether the risk for cancer was related to the MS disease process itself or to prior IS exposure. The most common types of cancer evaluated included colon/rectal cancer, female breast cancer, and leukemia.
The investigators estimated a crude incidence rate for cancer of 2.26% (2.02% in women; 2.7% in men). Risk for cancer among patients exposed to IS therapy was higher than in those not exposed to IS treatment (adjusted hazard ratio, 11.05; 95% CI, 1.67-73.3; P =.013). The risk for cancer observed among patients with MS who received IS treatment appeared to be related to duration of exposure and cumulative IS dose, not to the specific IS agent used. Notably, the results of the study did not demonstrate an association between MS and cancer.
On the basis of these findings, the researchers emphasized the importance of careful selection of MS therapies to help modify patients’ risk for life-threatening diseases, including cancer. Studies on long-term outcomes among patients with MS are essential for balancing the efficacy of a particular therapy with its potential adverse effects.
Ragonese P, Aridon P, Vazzoler G, et al. Association between multiple sclerosis, cancer risk, and immunosuppressant treatment: a cohort study. BMC Neurol. 2017;17(1):155.