October 19, 2016

There are two women I know through multiple sclerosis social media groups who have recently heard the words ‘you have cancer’. And it got me thinking … what are the risks?  Are our MS bodies more vulnerable to cancer?  What about the disease modifying drugs that make living with MS tolerable? And so it got me researching. 

It depends

I like systematic reviews. As the name implies, the researchers have done the searching, read, cross checked and validated other work to test hypothesis and draw conclusions. I do get lost in some of the statistics, but luckily there are enough words that make sense.

I really recommend you read the 2015 systemic review published in the Multiple Sclerosis Journal.  I will do my best to summarise, but if you have a particular concern regarding a certain cancer or group of cancers, then this is a good starting point and will point you to the references. Thirty-eight studies evaluated the incidence or prevalence of cancer in MS patients.

Research limitations

The researchers identified some limitations which informed their proposed future research topics (is it sad that I can’t wait to read the next chapter in their research?)

• Did not consider disease-modifying drugs as a variable
• Considered studies from 1953 to 2010 with a high prevalence of European studies (68.4%), followed by North America (23.7%) and Asia (7.9%).  There was not mapping of the study population against cancer populations.
• A number of cancer registries were accessed, however these do not have high degree of accuracy in identifying MS patients, especially in mapping against MS patients who were not hospitalised..
• Although cancer registries have a high degree of accuracy in most jurisdictions, few studies using administrative data validated their approach to identifying the MS population or made efforts to identify persons with MS who were not hospitalized.

MS does not equal Cancer

Looking for a headline?  And I quote:  ”When compared to the general population, cancer incidence was most often reported as lower than in the MS population”.  But I know you want to know about individual cancers.  Again, I suggest you read the full article, but …

Brain and nervous system cancers

It made sense to me that eight  of the 38 studies would consider brain or nervous system cancers with MS - which obviously has a relationship with brain and nerves.  But I was also concerned that the higher use of MRIs and other scanning would ‘over diagnose’ brain and nervous cancers.

Rather than paraphrasing this section, I’ll quote straight from the paper (with the emphasis added): “Four of the incidence studies reported that the risk of developing a brain tumor did not differ statistically significantly between the MS and general populations. One study reported a reduced risk of brain tumors in the MS population. The other studies reported elevated risks of developing brain tumors. However, in one study that reported incidence rates by tumor type, this increased risk appeared to be largely driven by an increased risk of benign tumors (meningiomas)”.

So I am taking that as good news?

Breast

Both of my friends have breast cancer as well as MS.  Chrissy Amphlett died from breast cancer after fighting MS for years.  I was really scared at what the data would show.  Okay, breathe in.  Remember, more women get MS and that could distort the data.  Clutching at straws before I even read the paper.

The results are mixed.  Of the nine studies, four found no difference and two found reduced risk of breast cancer in MS patients as compared to the general population   Three indicated an increase.

Ladies, may the odds be forever in your favour.

Bone and Joint cancers

Good news - one study reported the prevalence of bone cancer among hospitalized MS patients over age 65 years was lower than in hospitalized patients without MS.  A further study found no increased risk for bone cancer among MS patients.

Digestive cancers

Is it because when we are diagnosed with a ‘stupid disease’ that we start eating better?  I dont know, but the good news is that these cancers are less among MS patients!

Endocrine system

After breast cancer, thyroid was the one I was most worried about.  So many of us on the MS FB sites have thyroid issues.  Did these relate to thyroid cancers?

Drum roll please, and I will quote directly from the paper:  ”Of the three studies reporting the incidence of thyroid cancer, only one found an increased risk in the MS population as compared to the general population, but this finding was not statistically significant after adjustment for age, sex and comorbidities”.  Okay, not the best news but it does make sense.

Eye and orbit cancers

Good news.  None of the three studies that considered ocular cancer found an increased risk for MSers.

Female genital system

More good news.  Seven of the eight studies found the risk was the same or lower for MS patients.

Male genital system

Good news.  The seven studies found the risk of prostate and testicular cancer were consistently lower in the MS population than in the general population.

Lymphoma, myeloma, hematopoietic, or lymphatic cancer

This was one of the largest groups of studies with nine of the 38 identified studies looking at malignancies including lymphoma, multiple myeloma, and leukemia. Two of these found no difference or non-significant increase in cancer risk for MS patients, one one reported a statistically significant decrease.  So, I’m taking that as good news.

Oral cavity and larynx

Good news - the four studies did not find any increase in oral cancer for MS patients.

Respiratory system

Mixed reviews, but generally good news.  Of eight studies, two found that lung cancer was lower in MS patients; seven studies found no difference and only one study found the risk was higher.

Skin

Five studies found no difference between MS patients and the general population for melanoma; however one study found that the risk of non-melanoma skin cancer was increased.

Urinary system

Mixed reviews.  Of the four studies that looked at urinary cancer in multiple sclerosis patients, one study found a statistically significant increase in incidence and smaller increases in the other three studies.  However in good news, two studies considered bladder cancer, finding no significant increase.

References

Ruth Ann Marrie, Nadia Reider, Jeffrey Cohen, Olaf Stuve, Maria Trojano, Per Soelberg Sorensen, Stephen C Reingold and Gary Cutter, A systematic review of the incidence and prevalence of cancer in multiple sclerosis, Multiple Sclerosis Journal 2015, Vol. 21(3) 294–304 Downloaded from msj.sagepub.com at Australian National University on October 19, 2016 Multiple Sclerosis Journal 21(3) 298 http://msj.sagepub.com