Study Examines Effects of Chemotherapy in Individuals with Cancer and MS

New findings from an analysis of data from the MSBase registry (MSBase.org) suggest that chemotherapy for cancer may be associated with a temporary protective effect against multiple sclerosis (MS) relapses, offering clinicians important real-world insights on disease-modifying therapy (DMT) management in this dual-diagnosis population. Results of this study were presented at the 41^st Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS).

The study was a retrospective cohort analysis which included 364 individuals with MS and cancer treated with chemotherapy who were observed for a median follow-up of 2.8 years. Researchers examined MS relapse rates and confirmed disability progression (CDP) over time between individuals with MS who received chemotherapy and similar MS patients who did not. To ensure a fair comparison, researchers used 2:1 matching based on key clinical factors, such as age, disability level, MS treatment history, and relapse rates. A separate analysis was also done for those with breast cancer who were followed for a median of 3.9 years.

In terms of results,

• Age was inversely associated with MS relapse risk (hazard ratio [HR] 0.90 per year; P <.001).
• Exposure to DMTs following chemotherapy did not significantly alter relapse rates or 6-month CDP.
• Chemotherapy use was associated with a reduction in MS relapse risk within the first year post-treatment (0–6 months: HR, 0.35 [95% CI, 0.17 to 0.75]; 6–12 months: HR, 0.39 [95% CI, 0.17 to 0.87]), although this effect was not sustained beyond 12 months.
• In the breast cancer subgroup, chemotherapy use was linked to reduced MS relapse risk relative to matched controls (HR, 0.58 [95% CI, 0.37 to 0.95]).