Cancer in multiple sclerosis patients following prolonged exposure to disease-modifying therapies (DMTs): a systematic review and meta-analysis.

Introduction: The current literature on the prevalence and potential association between disease-modifying therapies (DMTs) and cancer risk in the MS population has yielded mixed findings.

Methods: This study aimed to estimate cancer prevalence and cancer risk in patients with MS (PwMS) under prolonged DMT exposure. Database search include: MEDLINE PUBMED, SCOPUS, and Google Scholar.

Results: A total of 13 studies involving 333,779 PwMS were included, reporting cancer events over periods ranging from 6 to 32 years. The aggregated pooled prevalence of cancer events in MS patients receiving disease-modifying therapies (DMTs) was 3.8% (95% CI 2.6, 5.2%), with substantial heterogeneity (I = 99.7%, p = 0). Two studies compared cancer events in MS patients who received DMTs versus those who did not. The relative risk of cancer associated with DMTs was 0.8 (95% CI 0.59-1.31, I = 93.6%, p = 0.53), indicating no significant increase in cancer risk due to DMTs. Breast and basal cell carcinomas had a high prevalence (18.4% and 11.3, respectively) in PwMS under DMTs.

Conclusion: This study reports a 3.8% pooled prevalence of cancer in PwMS receiving DMTs. The findings of this study suggest that DMTs alone do not increase cancer risk in PwMS. Breast cancer and basal cell carcinoma had the highest prevalence among the different types of cancer.