MS may increase risk of dying from colorectal cancer

Study raises questions about why people with multiple sclerosis face lower survival rates after a cancer diagnosis.

Dave Yasvinski 4 minute read September 17, 2021
woman with cancer looking into mirror

What is it about multiple sclerosis that determines the outcomes of a cancer diagnosis? GETTY

A new study has found that people with multiple sclerosis who develop colorectal cancer may be more likely to die from the cancer, or any other cause, over the next year than people with only cancer.

The study, which was supported by the MS Society of Canada and published in the journal Neurology, found that people with MS were 45 per cent more likely to die from any cause six months after receiving a cancer diagnosis — and 34 per cent more likely to die by the one year mark — than those with cancer but not MS. “These results warrant further investigation to determine what factors may lead to shorter survival times,” said Ruth Ann Marrie, author of the study at the University of Manitoba.

“Are people with MS less likely to receive cancer treatment? Or are they less able to tolerate the effects of chemotherapy? Are factors specific to MS involved? How accommodating is the cancer care system for people with disabilities? These are among the many questions that need to be investigated.”

Canada has one of the highest rates of multiple sclerosis in the world, with one in 400 — or over 900,000 people — living with the disease, according to the MS Society. There are roughly 2.8 million people suffering from MS globally, with prevalence having increased in every area of the world since 2013. The unpredictable disease attacks the body’s myelin — the layer of insulation protecting nerves — causing inflammation and disrupting nerve impulses throughout the central nervous system. Depending on the area of attack, this disruption can lead to a wide range of symptoms, including diminished vision, memory, balance and mobility, to name a few.

Depression is one of the most common symptoms of multiple sclerosis, with previous research suggesting the lifetime prevalence of the mood disorder to be as high as 50 per cent in MS patients. Untreated, depression can decrease quality of life and exacerbate other symptoms, including fatigue, pain and cognitive changes.

To arrive at their findings, researchers analyzed the health records of 338 people with MS and colorectal cancer residing in Manitoba and Ontario. Participants were matched with four people of the same age, sex and year of cancer diagnosis but not MS — a total of 1,352 subjects. Study participants had an average age of 65 at the time of diagnosis.

After passing the one-year mark, researchers found the risk of all-cause death for MS patients with cancer became the same for cancer patients without MS. The team adjusted for other factors that can increase the risk of all-cause death, including age, socioeconomic status and comorbidities. With regards to death from cancer specifically, MS patients were only more likely to die at the six-month mark, at which point they faced 29 per cent greater risk.

Over a five-year period, the all-cause rate of death for MS patients in Ontario was 16.4 per 100 person-years — a metric that takes into account the number of people in a study as well as time spent in the study. This number was 11.5 per 100 person-years for those without MS. In Manitoba, these numbers were 19.8 and 15.4, respectively.

When it comes to deaths caused by cancer, the fatality rate in Ontario was 12.7 per 100 person-years for those with MS compared to 9.9 for those without MS. In Manitoba, it was 13.6 for those with MS and 13.0 for those without.

The study, which researchers said may not have accounted for all other conditions participants may have had in addition to MS or cancer, sheds light on the unique challenges faced by people fighting life-threatening battles on multiple fronts.

“Understanding more about the factors involved in treating cancer in people with MS and their outcomes will be helpful for people with MS and their doctors as they balance the benefits of cancer treatment with the potential adverse effects and consider life expectancy and quality of life,” Marrie said.

Dave Yasvinski is a writer with Healthing.ca