Breast (female), colorectal, and lung cancer survival in people with intellectual or developmental disabilities: A population-based retrospective cohort study.

OBJECTIVES: Cancer is a leading cause of death among people living with intellectual or developmental disabilities (IDD). There is little empirical evidence documenting survival or comparing outcomes to those without IDD. This study investigated the association between IDD and cancer survival among adults with breast (female), colorectal, or lung cancer. METHODS: A population-based retrospective cohort study was conducted in Ontario, Canada, with routinely collected data. Patients with breast, colorectal, or lung cancer were included (2007‒2019). IDD status before cancer was determined using an established administrative data algorithm. The outcomes of interest included death from any cause and death from cancer. Cox proportional hazards models and competing events analyses using multivariable cause-specific hazards regression were completed. Analyses were stratified by cancer type. Interactions with age, sex, and stage at diagnosis, as well as sensitivity analyses, were completed. RESULTS: The final cohorts included 123,695 breast, 98,809 colorectal, and 116,232 lung cancer patients. Individuals with IDD experienced significantly worse survival than those without IDD. The adjusted hazard ratios of all-cause death were 2.74 (95% CI 2.41‒3.12), 2.42 (95% CI 2.18‒2.68), and 1.49 (95% CI 1.34‒1.66) times higher for breast, colorectal, and lung cancer patients with IDD relative to those without. These findings were consistent for cancer-specific deaths. With few exceptions, worse survival for people with IDD persisted regardless of stage at diagnosis. CONCLUSION: People with IDD experienced worse cancer survival than those without IDD. Identifying and intervening on the factors and structures responsible for survival disparities is imperative.

RéSUMé: OBJECTIFS: Le cancer est l'une des principales causes de mortalité chez les personnes vivant avec des déficiences intellectuelles ou des troubles du développement (DI/TD). Il y a peu de preuves empiriques décrivant la survie de ces personnes lorsqu'elles sont atteintes d'un cancer ou comparant leurs résultats à ceux des personnes sans DI/TD. Notre étude porte sur l'association entre les DI/TD et la survie au cancer chez les adultes atteints de cancer du sein (femmes), du colorectum ou du poumon. MéTHODE: Une étude de cohorte rétrospective populationnelle a été menée en Ontario, au Canada, à l'aide de données recueillies systématiquement. Nous avons inclus les patientes et les patients atteints de cancer du sein, du colorectum ou du poumon (2007‒2019). Nous avons identifié la présence des DI/TD avant le cancer à l'aide d'un algorithme de traitement de données administratives reconnu. Les résultats d'intérêt étaient les décès de toutes causes et les décès dus au cancer. Nous avons appliqué des modèles des risques proportionnels de Cox et des analyses des événements concurrents en utilisant la régression multivariée des risques par cause. Nos analyses ont été stratifiées selon le type de cancer. Nous avons tenu compte des interactions avec l'âge, le sexe et le stade au diagnostic et effectué des analyses de sensibilité. RéSULTATS: Les cohortes finales ont inclus 123 695 personnes atteintes de cancer du sein, 98 809 atteintes de cancer colorectal et 116 232 atteintes de cancer du poumon. La survie des sujets ayant des DI/TD a été significativement moins bonne que celle des sujets sans DI/TD. Les rapports de risques instantanés ajustés pour les décès de toutes causes étaient 2,74 fois (IC de 95 % 2,41‒3,12), 2,42 fois (IC de 95 % 2,18‒2,68) et 1,49 fois (IC de 95 % 1,34‒1,66) plus élevés chez les personnes atteintes de cancer du sein, du colorectum et du poumon et ayant des DI/TD que chez les personnes sans DI/TD. Ces constatations ressortent pour tous les décès attribuables à des cancers particuliers. Avec peu d'exceptions, la survie moins bonne pour les personnes ayant des DI/TD persistait quel que soit le stade au moment du diagnostic. CONCLUSION: La survie au cancer était moins bonne chez les personnes ayant des DI/TD que chez celles n'ayant pas de DI/TD. Il est impératif d'identifier les facteurs et les structures responsables de ces disparités dans la survie et d'intervenir en conséquence.

Stage IV breast, colorectal, and lung cancer at diagnosis in adults living with intellectual or developmental disabilities: A population-based cross-sectional study.

BACKGROUND: Cancer is a leading cause of death among people living with intellectual or developmental disabilities (IDD). Although studies have documented lower cancer screening rates, there is limited epidemiological evidence quantifying potential diagnostic delays. This study explores the risk of metastatic cancer stage for people with IDD compared to those without IDD among breast (female), colorectal, and lung cancer patients in Canada. METHODS: Separate population-based cross-sectional studies were conducted in Ontario and Manitoba by linking routinely collected data. Breast (female), colorectal, and lung cancer patients were included (Manitoba: 2004-2017; Ontario: 2007-2019). IDD status was identified using established administrative algorithms. Modified Poisson regression with robust error variance models estimated associations between IDD status and the likelihood of being diagnosed with metastatic cancer. Adjusted relative risks were pooled between provinces using random-effects meta-analyses. Potential effect modification was considered. RESULTS: The final cohorts included 115,456, 89,815, and 101,811 breast (female), colorectal, and lung cancer patients, respectively. Breast (female) and colorectal cancer patients with IDD were 1.60 and 1.44 times more likely to have metastatic cancer (stage IV) at diagnosis compared to those without IDD (relative risk [RR], 1.60; 95% confidence interval [CI], 1.16-2.20; RR, 1.44; 95% CI, 1.24-1.67). This increased risk was not observed in lung cancer. Significant effect modification was not observed. CONCLUSIONS: People with IDD were more likely to have stage IV breast and colorectal cancer identified at diagnosis compared to those without IDD. Identifying factors and processes contributing to stage disparities such as lower screening rates and developing strategies to address diagnostic delays is critical.