Co-morbid MS lowers survival rate in colorectal cancer

People with MS had lower overall and cancer-specific survival soon after colorectal cancer diagnosis compared with those without MS, according to results of a retrospective matched cohort study published in Neurology.

“Although cancer is a serious illness, and a good understanding of prognosis is important for clinical decision-making, there is very little MS-specific information about cancer prognosis,” Ruth Ann Marrie, MD, PhD, of the department of internal medicine at the University of Manitoba’s Max Rady College of Medicine in Canada, told Healio Neurology. “We sought to address this issue. We also hoped that our findings would prompt further study of other aspects of the cancer care pathway.”

The investigators used population-based administrative data in Manitoba and Ontario to identify individuals with MS according to a validated case definition. To identify people with MS and colorectal cancer (n = 338) they linked the cohorts to cancer registries. Further, they selected individuals with colorectal cancer and without MS (n = 1,352), matched in a 4:1 ratio on birth year, sex, cancer diagnosis year and region. Mean age at cancer diagnosis was 64.7 years.

Marrie and colleagues compared all-cause survival between cohorts using Cox proportional hazards regression, adjusted for age at cancer diagnosis, cancer diagnosis year, income, region and Elixhauser comorbidity score. They used a cause-specific hazards model to compare cancer-specific survival between cohorts and a random-effects meta-analysis to pool findings across provinces. They adjusted for cancer stage and disability status, measured according to use of home care or long-term care services, via complementary analyses that used a subcohort from Ontario.

Results showed a post-adjustment association between MS and increased risk for all-cause death, which was highest 6 months after diagnosis (HR = 1.45; 95% CI, 1.19-1.76) and declined over time (HR, 1 year = 1.34; 95% CI, 1.09-1.63; HR, 2 years = 1.24; 95% CI, 0.99-1.56; HR, 5 years = 1.1; 95% CI, 0.8-1.5). Moreover, MS was linked to increased cancer-specific death at 6 months after diagnosis only (HR = 1.29; 95% CI, 1.04-1.61). MS correlated with an increased risk for death due to any cause (HR = 1.6; 95% CI, 1.16-2.21) and with cancer-specific death (HR = 1.47; 95% CI, 1.02-2.12) after adjusting for cancer stage. After adjusting for disability status, the associations between MS and all cause death (HR = 1.37; 95% CI, 0.97-1.92) and cancer-specific death (HR = 1.34; 95% CI, 0.91-1.97) were partially attenuated.

“While our findings should be confirmed in other jurisdictions, they provide clinicians and people with MS with additional prognostic information that they can consider,” Marrie said. “To really guide practice, our findings need to be supplemented by additional investigations that clarify why outcomes were worse.”