Investigating the impact of intellectual and developmental disability on the stage of colorectal cancer at diagnosis among adults in Ontario

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Authors
Biggs, Kelly
Keyword
colorectal cancer , Intellectual and developmental disability , intellectual disability , disability , cancer stage
Abstract
Background: Colorectal cancer is one of the most commonly diagnosed cancer and the second leading cause of cancer death worldwide. Individuals with intellectual and developmental disability (IDD) are vulnerable to cancer care disparities, however, there is currently no published research assessing the association between IDD and colorectal cancer stage at diagnosis. Methods: This was a population-based cross-sectional study of adults aged 18 years or older in Ontario with a diagnosis of colorectal cancer between January 1, 2007 and December 31, 2019. The study used Ontario health administrative databases held at ICES and linked to the Ontario Cancer Registry. Each adult was assigned as with or without IDD based on an Ontario specific algorithm using captured health service use. The association between IDD status and colorectal cancer stages at diagnosis (unknown and metastatic) were examined using multivariable log-binomial regression models adjusted for age and sex. Sensitivity analyses were performed to assess the robustness of our results. Results: The main study cohort consisted of 81,501 colorectal cancer cases diagnosed between January 1, 2007 and December 31, 2019. Of the 399 cases among adults living with IDD, 98 had an unknown stage (24.6%) compared to 11,703 of the 81,102 cases among adults without IDD (14.4%). Adults living with IDD were 1.8 times more likely to be diagnosed with unknown stage of colorectal cancer compared to adults without IDD (95% CI: 1.52-2.14). After excluding colorectal cancer cases with an unknown stage, the study cohort consisted of 69,700 colorectal cancer cases. Of the 301 cases among adults living with IDD, 89 had metastatic stage (29.6%) compared to 13,931 of the 69,399 cases among adults without IDD (20.1%). Adults living with IDD were 1.45 times more likely to be diagnosed with metastatic stage colorectal cancer compared to adults without IDD (95% CI: 1.22-1.73). Conclusion: A higher proportion of adults living with IDD are diagnosed with an unknown stage and metastatic stage of colorectal cancer at diagnosis compared to adults without IDD. Future work needs to understand why these inequities exist for adults living with IDD and identify effective interventions.
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