MS Possibly Linked to Greater Cancer Risk in Large, But Preliminary Norwegian Study

People with multiple sclerosis (MS) may have a greater overall risk of developing cancer than the general population, according to the results of a 58-year follow-up study of nearly 7,000 patients in Norway. Risk seems particularly high for cancers in respiratory organs, urinary organs, and the central nervous system.

Siblings of MS patients who do not have the disease themselves also may be at greater risk of blood cancers, the study suggests.

The findings, which are preliminary, were shared at the 5th Congress of the European Academy of Neurology (EAN), held recently in Oslo, Norway. The presentation, by study leader Nina Grytten, PhD, was titled “Cancer risk in multiple sclerosis patients, siblings, and healthy controls: a prospective, longitudinal cohort study.” The abstract is on page 31.

“This study is the first to compare cancer risk in MS with non-affected siblings of MS patients. The risk assessment between these two groups is extremely interesting because they share the same genetics and environmental conditions,” Grytten, of Haukeland University Hospital, said in a press release.

Drawing on patient health records, researchers analyzed data from 6,935 people with MS, born between 1930 and 1979. The patients were registered in several MS and cancer registries, or prevalence studies in Norway. The analysis also included data from 9,346 siblings without MS, and 38,055 non-MS subjects, during a total of 58 years of follow-up.

Compared with people without the neurodegenerative disorder, MS patients had a particularly greater risk of three cancers: respiratory, with a 66% increased risk; central nervous system, specifically cancer in the brain or spinal cord, with a 52% increased risk; and urinary, with a 51% increased risk.

However, compared with their siblings, those with MS did not have an overall increased cancer risk, the study found. According to the team, this was possibly “due to a higher risk of hematological cancer in non-MS siblings, both compared to patients, and compared to non-MS controls.” Hematological, or blood cancers include myeloma, lymphoma, and leukemia.

According to Grytten, this observation suggests that MS and blood cancer may share a common cause or origin, which can be important for future MS treatments and prevention of both diseases.

“This research outlines the need for greater awareness of cancer risk among MS patients, which should lead to shortened cancer diagnosis, and more effective therapy in order to improve outcomes and survival,” Grytten said.

However, the researcher emphasized that previous clinical studies regarding cancer risk in MS patients have shown “inconsistent findings.” Thus, more research is needed to improve scientists’ understanding in this area.

Indeed, the National MS Society emphasized that these results “should be considered preliminary,” noting that “no information was provided about the use of disease-modifying therapies or other possible contributing factors in people included in this study.”

“This study does not suggest that MS causes cancer,” the MS Society said.