People with multiple sclerosis (MS) have a lower overall lifetime risk of cancer relative to a general population matched by area, age, sex and habits like tobacco use and alcohol consumption, new research reports, suggesting this lesser risk might be due to the nature of MS itself or to disease modifying therapies used by patients.
The study, “Decreased prevalence of cancer in patients with multiple sclerosis: A case-control study,” was published in the journal PLOS ONE.
The immune system is known to play a large role in both MS and cancer, leading some scientists to suggest that a disease like MS would modify the risk of cancer.
Some argue that the highly active immune system seen in MS patients works to improve cancer surveillance and decrease cancer risk. But others point to the disease-modifying treatments used by MS patients, particularly immunosuppressives, as increasing cancer risk in this population.
Studies have shown conflicting results, with some indicating a higher cancer risk and others a lower risk in MS patients.But most of these studies do not take into account lifestyle factors associated with cancer development, including alcohol and tobacco use.
Researchers at the Université Clermont Auvergne, in France, set out to better determine lifetime cancer prevalence in MS patients.
They conducted a case-control study by self-administered questionnaire; in total, 1107 responses were used for the analysis. The same survey was also given to 1,568 healthy people, serving as controls, in the Auvergne region. Age, gender, and history of smoking and alcohol use were taken into account.
Results showed that 7.32 percent of MS patients had been treated fro cancer, whereas the disease affected 12.63 percent of those in the control group. Cancer frequency by type was not part of the study, but the most prevalent cancer reported in patients was breast cancer, which the researchers said “would be expected in a population of middle-aged women.”
Statistical analysis found that MS patients, overall, were 37 percent less likely to develop cancer compared to the control group — and neither DMT use, including immunosuppressants, nor disease course appeared to increase cancer risk among patients.
“MS was associated with a reduced overall cancer risk,” the researchers wrote. “Classical immunomodulator (beta-interferons and glatiramer acetate) and immunosuppressant use was not associated with an increased overall cancer risk, but there is not sufficient data to draw firm conclusions.”
This lower risk, the team wrote, might be due to the physiological nature of MS itself. The disease is a product of autoimmunity — referring to the hyper-sensitivity of the immune system to self-antigens — and this could lead to increased immune vigilance against cancer cells.
It might also be linked to the very use of DMTs. In fact, the researchers noted that several DMTs are currently being investigated for potential anti-tumor activity, including dimethyl fumarate (an approved MS treatment, under the brand name Tecfidera) in colon cancers, fingolimod (brand name, Gilenya) in various cancers, and teriflunomide (brand name, Aubagio) in triple-negative breast cancers.