Relative Cancer Risk is Higher in MS Patients Who Switch Disease-modifying Treatments More Frequently, Study Finds

Relative Cancer Risk is Higher in MS Patients Who Switch Disease-modifying Treatments More Frequently, Study Finds

The relative risk of developing cancer was found to be higher in multiple sclerosis (MS) patients who more frequently switched between disease-modifying treatments, according to a study.

In addition, researchers found an increased incidence of cancer in male MS patients from 20 to 50 years old, and in female MS patients over 50.

The data were reported in the study “Cancer Risk and Multiple Sclerosis: Evidence From a Large Italian Cohort,” published in the journal Frontiers in Neurology.

Previous research has discovered that MS and cancer may share some abnormal functions of the immune system.

To better understand the incidence of cancer in MS patients, and evaluate the impact of disease-modifying treatments (DMTs) on cancer risk, a team led by researchers at the University of Catania, Italy, compared a database of MS patients between 2003 and 2013 in Catania (the second largest city of Sicily in Italy) with the Integrated Cancer Registry of Catania-Messina-Siracusae-Enna, which collects information about cancer in the general population of that particular geographic area.

During the time period analyzed (2003–2013), 2,730 people were diagnosed with MS. Of these, 1,180 patients satisfied the inclusion criteria and were enrolled in the study (67.1% females; mean age of 41.2 years), and of those, a total of 36 incidences of cancer were observed.

Investigators then analyzed the number of cancer cases according to the “expected” number of cases in the Catania community based on the Integrated Cancer registry. These are the “standardized incidence ratios,” or SIR.

If the observed number of cancer cases in MS patients equals the expected number, the SIR is 1, meaning no increased cancer risk. If more cases are observed than expected, the SIR is greater than 1, meaning increased risk. If fewer cases are observed than expected, the SIR is less than 1, meaning less risk.

The results showed that the cancer risk was not significantly increased in the MS population as a whole (SIR of 1.18). However, when the analysis was focused on specific population subgroups, stratified based on age and gender, men between 20 and 50 years old (SIR of 2.84), and women over 50 (SIR of 1.82) showed a significantly higher risk of developing cancer.

These results suggested that some MS subpopulations may be more susceptible to developing cancer.

The team also investigated the effects of different MS treatment strategies on the relative risk (RR) of developing cancer. MS patients were divided into four subgroups: patients not treated with any disease-modifying treatment (DMT), treated with one DMT (“no switch”), treated with two DMT (“one switch”), and treated with more than two DMTs.

The RR of developing cancer was not significantly higher in the “no DMT” group, and slightly increased in the “no switch” group, but it was 1.99 (nearly two times higher) in the “one switch” group, and 3.38 (more than three times higher) in the group who switched at least twice.

Based on the results, the team hypothesized that “MS patients experiencing therapeutic failure with different immunomodulating and/or IS (immunosuppressive) [agents] could have an enhanced risk of cancer, because being exposed to different molecules with different mechanisms of action may negatively influence the innate and adaptive immune systems and make these patients more sensitive [to] carcinogenesis [cancer formation].”

In terms of cancer types, a significantly higher incidence of genitourinary and thyroid cancers was observed.

Additional analysis showed that age, age at MS onset, disease duration, and more that two DMT switches were associated with a higher risk of developing cancer.

“Our results demonstrated that cancer risk was not increased in our MS population; but age and sex different distribution may partly drive cancer risk. Higher cancer risk in MS patients switching more than two DMTs should [be] take[n] into account in treatment decision making,” the team concluded.


  1. Cindy W Edwards says:

    I was diagnosed with Multiple Sclerosis (MS) in October 2012, at the age of 44. I woke up one morning with numbness in my lower back and legs, I couldn’t feel my feet touching the floor. I saw my doctor and had an MRI to see if I had a disc problem, it was negative and she told me she feared MS. I was sent to a neurologist, had two more MRIs, and was told that night that I have four lesions on my spine MS. I tried every shots available but nothing worked. In 2015, my neurologist and I decided to go with natural treatment and was introduced to Organic Herbal Clinic natural organic MS Herbal formula, i had a total decline of symptoms with this treatment, the numbness, terrible back pains, stiffness, body weakness, double vision, depression and others has subsided. Visit Organic Herbal Clinic official website www. organicherbalclinic. com This treatment is a breakthrough for all suffering from Multiple sclerosis, i am strong again!

  2. Robin says:

    Excellent, as if I didn’t have enough to worry about already. Isn’t it possible that people who have been on more than two DMTs have particularly maladaptive immune systems in the first place, that make it more likely that they will develop cancer?

    • Alberto Molano says:

      I guess the short answer is: there is not enough evidence to support or reject your hypothesis. The three possibilities are: 1. The long-term exposure to different medicines play a role. 2. The overactive, poorly controlled immune system plays a role. 3. Both. Also, some people switch DMT due to their side effects, like headache or nausea, not because the DMT is not working.

  3. Jayne says:

    Maybe that’s why I got breast cancer when I turned 40. Started Copaxone about 8 years ago,switched to Rebif, then Tysabri, then Tecfidera, back to Tysabri and then breast cancer.

  4. Christopher says:

    The human body is constantly fighting off mutated cells (essentially– cancer). But when the immune system can’t keep up, cancers happen. With heavy duty immunosuppressants, the cancer cells have a better chance of proliferating out of control because there isn’t a hearty enough immune system to mount a successful attack.

    As far as a “maladaptive” immune system… there really isn’t such a thing as far as concerning multiple sclerosis. There is something–or possibly many things–that causes the immune system to turn against the host (autoimmunity), whether the immune system is working proficiently or not. It is more of instances of the immune system not being able to win because it’s fighting on too many fronts–kind of a numbers game.

  5. Demelza says:

    Can anyone elaborate on the financial/budgetary effects of MS? What to do when PT for MS costs $140/hour and one needs 2 PT sessions a week that is not covered by insurance? There is so much that is needed that is not covered but can be very helpful, what is the best way to conserve funds without foregoing necessary treatment?

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