Occurrence of malignant diseases in patients with multiple sclerosis: population-based MS Registry data

Among different comorbidities occurring in multiple sclerosis (MS), the presence of malignant diseases in these patients is of the particular importance. The aim of this study was to determine the malignant diseases burden in a whole cohort of patients with MS in the Belgrade region, based on the Belgrade population registry data.

This study comprises 2725 MS patients from the MS Registry, which represents a source for all necessary demographic and clinical data. Firstly, the Registry was searched for all persons with MS who had cancer comorbidity, during the period 1996-2019. Diagnosis of cancer was validated by the patients' medical documentation. In order to investigate factors associated with the occurrence of any type of the cancer and/ or breast cancer only, in persons with MS, different logistic regression analyses were performed.

A total of 64 persons with 69 malignant diseases were observed (prevalence 2.53%). The most frequent malignancies in males were skin cancer (50.0%) and in females, breast cancer (23.2%). The cumulative incidence of cancer comorbidity in persons with MS was 324.9 new cases per 100,000 person-years for the total population (137.6/100,000 in males and 403.6 per 100,000 in females). Comparison of cancer incidence rate between MS and general Belgrade population revealed lower risk for malignancy occurrence in the MS population in total (standardized incidence ratio, SIR = 0.58, 95% CI 0.16-1.49).

Our findings demonstrate that MS patients in the Belgrade region have lower risk for the development of malignancy than age- and sex-matched general population.