Cancer Risk Among Patients With Multiple Sclerosis

Background and objectives: Previous literature has been diverging on cancer risk in people with multiple sclerosis (PwMS). Therefore, this study compared the risk of cancer in PwMS and a matched sample from the French general population.Methods: This 10-year nationwide retrospective matched cohort study (2012-2021) used data from the national French administrative health care database (99% coverage of the French population) to determine the time to the first incident cancer. PwMS were identified using their long-term disease (LTD) status, hospitalizations, and multiple sclerosis (MS)-specific drug reimbursements. The control population was matched 4:1 on age, sex, residence, insurance scheme, and cohort entry date. Participants were included if they had no history of cancer in the 3 years before inclusion. Patients with cancer were identified through LTD status, hospitalizations, chemotherapy, radiotherapy, or prostate cancer-specific drug reimbursements. Overall and cancer location-specific hazard ratios (HRs) for the first incident cancer were obtained from Fine and Gray models, and age- and sex-stratified estimates were reported. Participation in cancer screening through the 3 national programs (breast, colorectal, and cervical) were compared between groups.Results: Cancer incidence was 799 per 100,000 person-years (PYs) (n = 8,368) among the 140,649 PwMS and 736 per 100,000 PYs (n = 31,796) among the 562,596 matched controls (70.8% of women; follow-up: 7.6 ± 3.2 years). A small overall risk increase was observed for PwMS (HR 1.06, 95% CI 1.03-1.08), mostly in women (HR 1.08, 95% CI 1.05-1.11). Risk varied by cancer types and was lower for prostate (HR 0.80, 95% CI 0.73-0.88), breast (HR 0.91, 95% CI 0.86-0.95), and colorectal (HR 0.90, 95% CI 0.84-0.97) cancer and higher for bladder (HR 1.71, 95% CI 1.54-1.89), brain (HR 1.68, 95% CI 1.42-1.98), and cervical (HR 1.24, 95% CI 1.12-1.38) cancer in PwMS. Cancer risk was higher in PwMS younger than 55 years (HR 1.20, 95% CI 1.15-1.24) but decreased in PwMS aged 65 years and older (HR 0.89, 95% CI 0.85-0.94). This trend was found in all cancer locations. There were fewer PwMS getting screened than controls (all programs), with a particularly pronounced difference among those aged 65 years and older.Discussion: Cancer risk was slightly increased in PwMS, particularly for urogenital cancers, possibly due to surveillance bias. Risk fluctuated depending on age, perhaps due to varying generational screening prac