Multiple Sclerosis and Cancer Risk, Conflicting Data
Living with multiple sclerosis (MS) is a big enough challenge, and now a new study suggests the presence of this neurodegenerative disease also may be associated with a greater risk of developing cancer. This announcement conflicts with some (but not all) previous research, and so it’s worth taking a look at what scientists have to say on the topic.
MS and cancer: new study
The new research appears in the European Journal of Neurology and involved data on 1,292 individuals with MS who were each matched with four nonaffected controls. All the study subjects were part of the National Health Insurance System of Taiwan.
The authors discovered the following:
- Individuals who had MS were 85 percent more likely to develop cancer than were controls
- Among people with MS, the risk of developing breast cancer was more than twofold greater than among controls
Because these findings are not in line with those of previous studies, the authors suggested there may be environmental and genetic influences associated with Taiwan that differ from those of other locations. For now, the reasons behind these findings are unknown.
Previous studies of MS and cancer
In a study from British Columbia, Canada, published in 2012, the investigators looked at both cancer risk and tumor size among 6,820 patients with MS and compared them with the general population. The findings of this analysis differed from that of the new study. Here’s how:
- Overall risk of cancer among patients with MS was lower than it was among the general population
- Risk of colorectal cancer was significantly reduced when compared with lung, breast, and prostate cancers
- Among patients with MS who developed cancer, tumor sizes were larger than expected, which suggested diagnostic neglect
Yet another study evaluated the effect of the type of MS treatment (i.e., immunomodulatory drugs) on cancer risk. The medications analyzed included glatiramer acetate, beta-interferons (1a and 1b), and intravenous immunoglobulins.
The incidence of cancer among the Israeli MS patients was examined for the years 1960 to 2003. Here’s what the authors found:
- Of the 892 females with MS, 1.7 percent (15) developed breast cancer and 3.5 percent (31) developed any cancers.
- Of the 446 males with MS, 3.8 percent (17) developed cancer
- Overall, the incidence of cancer among female MSers was significantly lower than among the general population
- Female MSers who took glatiramer acetate had a greater rate of breast cancer and all MS patients who received beta-interferons had a higher risk of non-breast cancers, but the risk was not statistically significant
One more study was conducted among Danish patients with MS. The data came from the Danish Multiple Sclerosis Register and the Danish Cancer Register and included 11,817 MS patients. Here are the findings:
- A total of 1,037 cancers were identified among the MS patients compared with 1,098 expected in the general population
- Overall risk of cancer was not greater but female MS patients did show a modest excess risk of breast cancer
- Men with MS showed a 16 percent reduced risk of cancer of the respiratory, digestive, and genital organs
The bottom line
Based on the findings of these four studies from around the globe, it seems there may be a small increased risk of breast cancer among women with MS. Overall, however, the risk of cancer appears to be lower than among the general population with the exception of Taiwan.
Achiron A et al. Cancer incidence in multiple sclerosis and effects of immunomodulatory treatments. Breast Cancer Research and Treatment 2005 Feb; 89(3): 265-70
Kingwell E et al. Cancer risk in multiple sclerosis: findings from British Columbia, Canada. Brain 2012 Oct/ 135(Pt 10): 2973-79
Nielsen NM et al. Cancer risk among patients with multiple sclerosis: a population-based register study. International Journal of Cancer 2006 Feb 15; 118(4): 979-84
Sun L-M et al. Increased breast cancer risk for patients with multiple sclerosis: a nationwide population-based cohort study. European Journal of Cancer 2014 Jan