A new study, published in Neurology, explores whether multiple sclerosis (MS) may be linked to a higher risk of certain cancers. Conducted by researchers at Rennes University in France, the study found a slight increase in the incidence of cancers like bladder, brain, and cervical cancer among people with MS compared to those without the condition. However, researchers emphasize that the study only shows an association, not a direct cause-and-effect relationship.
MS is a chronic autoimmune disease where the body’s immune system attacks myelin, the fatty substance that insulates and protects nerves. The condition can be unpredictable and disabling, with symptoms that vary widely.
“People with MS undergo an increased number of tests to monitor MS, making it more likely to detect other diseases,” said study author Emmanuelle Leray, PhD. “We found an association between some types of cancer and MS which may have different explanations depending on a person’s age and the types of cancer. Overall, our study found the increased risk of cancer was quite small.”
In the study, researchers analyzed data from the French national healthcare database over a 10-year period. They compared 140,649 people with MS to 562,596 people without MS, matching them by age, sex, and residence. Participants were cancer-free three years before the study began and were followed for an average of eight years.
During this period, 8,368 people with multiple sclerosis and 31,796 people without MS developed cancer. Researchers calculated 799 cancers per 100,000 person-years for people with MS, compared to 736 cancers per 100,000 person-years for those without MS. This translates to a 6% overall increase in cancer risk for those with MS.
Age appeared to influence the cancer risk, as the study found a higher risk of cancer in individuals under 55 with MS, but a lower risk for those over 65 when compared to people without multiple sclerosis. Researchers also examined specific cancer types. The results showed a 71% increased risk of bladder cancer, a 68% increased risk of brain cancer, and a 24% increased risk of cervical cancer in people with MS. In contrast, they had a 20% lower risk of prostate cancer, a 10% lower risk of colorectal cancer, and a 9% lower risk of breast cancer.
“While our study found a higher risk for brain cancer, it may be due in part to earlier detection in those with MS since they regularly have brain scans which may detect cancers earlier, before a person has symptoms,” said Leray. She noted that factors like frequent urinary tract infections and the use of immunosuppressant drugs might contribute to the elevated risk of bladder and cervical cancers among MS patients.
The study also observed a lower risk for colorectal and breast cancers in people with MS, which could be related to reduced cancer screening as individuals with MS age and experience more severe symptoms. “The lower risk for colorectal and breast cancers may be due in part to fewer people with MS getting screened for cancer in older age when they may be experiencing more MS symptoms,” Leray added.
One limitation of the study was the lack of information on certain lifestyle factors such as education, income, smoking, and alcohol consumption. The researchers call for further studies that examine how these factors, along with cancer screening practices, might affect cancer risk in people with MS.
