The finding, from a study published on September 15 in the journal Neurology, suggests that people with MS may opt against chemotherapy or other cancer treatments, due to the impact of potential side effects on their chronic condition, the researchers say. “Our study doesn’t address why the link exists, but we can speculate,” says study coauthor Ruth Ann Marrie, MD, PhD, director of the MS Clinic at the University of Manitoba in Winnipeg, Canada. “It’s possible that people with MS are undertreated for colon cancer, or that they don’t tolerate cancer and its treatments as well as people without MS,” Dr. Marrie says. The progressive disability seen with more advanced stages of MS may also affect their ability to withstand the effects of colon cancer and its treatment, she adds. RELATED: Breast Cancer and MS Study: Mixed Results

Risk of Death From Any Cause Higher 6 Months and 1 Year After Diagnosis

For the study, Marrie and her colleagues looked at the health records for 338 people with MS and colorectal cancer who lived in the provinces of Ontario and Manitoba in Canada. Each study participant was matched with four people who had colon cancer but did not have MS and who were the same age and gender and had the same year of cancer diagnosis. Study participants were diagnosed with colon cancer at age 65 years, on average, according to the researchers. The researchers found that people with MS were 45 percent more likely to die of any cause within six months of their cancer diagnosis than people without MS. In addition, they were 34 percent more likely to die of any cause within one year of their diagnosis. After one year, the risk of death was the same for the two groups, those with or without MS, the researchers say. RELATED: 7 Ways to Prevent Colon Cancer

Risk of Death From Colon Cancer Also Higher 6 Months After Diagnosis

When it comes to colon cancer specifically, people with MS were 29 percent more likely to die from the disease than people without MS within six months, but not one year, of their diagnosis, the researchers note. This was after the researchers adjusted for other factors that could affect risk for cancer death, such as the participants’ age and socioeconomic status, as well as their having other conditions such as heart disease or diabetes, they say.

Furthermore, those with increased disability due to MS were 37 percent more likely to die overall, and 34 percent more likely to die from colon cancer, within one year of cancer diagnosis compared to those who didn’t have MS, according to the researchers.

More Research Needed to Improve Colon Cancer Prognosis for People With MS

Understanding more about the factors involved in treating cancer in people with MS will help those with the condition and their physicians as they balance the benefits of cancer treatment with the potential side effects and impact on quality of life, Marrie says. “This study provides some information about prognosis for people with MS, which can be discussed with their clinicians as they make decisions,” she explains. “We don’t have enough information to change treatment for colon cancer in people with MS based on our findings. However, our findings do point to the need to evaluate whether the higher [risk for death] we observed in people with MS reflects treatment differences, and how we could improve [prognosis].”