People with intellectual disability are at an increased risk of any cancer, as well as several specific cancer types. The findings from a population-based cohort study of Swedish children born to mothers from the Nordic countries suggest a need for extended surveillance and early intervention in cancer among people with intellectual disability. Excess cancer risk was higher for syndromic intellectual disability. The results are presented by Dr. Qianwei Liu of the Institute of Environmental Medicine, Karolinska Institutet in Stockholm on behalf of the research team from Sweden during the proffered paper session on supportive and palliative care at ESMO Congress 2021 (16-21 September).

Dr. Liu explained in the study background that a large gap in knowledge about the risk of cancer in people with intellectual disability. Together with colleagues, Dr. Liu conducted a population-based cohort study of more than 3.5 million children of whom 27,956 (0.8%) were clinically ascertained cases of intellectual disability; they were born from 1974 to 2013.

To examine the association between intellectual disability and cancer, incident cancers were identified from the Swedish Cancer Registry. The study team used Cox regression models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) as measures of cancer risk in relation to intellectual disability after detailed adjustment for potential confounding. They separately analyzed severity and type of intellectual disability. Furthermore, they performed a sibling-comparison to investigate familial confounding.

The study team found a statistically significantly increased risk for any cancer (HR 1.57, 95% CI 1.35-1.82), as well as for several cancer types, in particular oesophageal (HR 28.4, 95% CI 6.2-130.6), stomach (HR 6.1, 95% CI 1.5-24.9), small intestine (HR 12.0, 95% CI 2.9-50.1), colon (HR 2.0, 95% CI 1.0-4.1), pancreatic (HR 6.0, 95% CI 1.5-24.8), uterus (HR 11.7, 95% CI 1.5-90.7), kidney (HR 4.4, 95% CI 2.0-9.8), central nervous system (HR 2.7, 95% CI 2.0-3.7), and other or unspecified sites (HR 4.8, 95% CI 1.8-12.9), as well as acute lymphoid leukaemia (HR 2.4, 95% CI 1.3-4.4) and acute myeloid leukaemia (HR 3.0, 95% CI 1.4-6.4).

Excess cancer risk was not modified by severity of intellectual disability or sex, but it was higher for syndromic intellectual disability. Little support for familial confounding was shown by sibling comparison.

The authors concluded that their results indicate a need for extended surveillance and early intervention in cancer among people with intellectual disability.

The study was supported by the European Union’s Horizon 2020 research and innovation programme, the Swedish Cancer Society, the Swedish Research Council for Health, Working Life and Welfare, and the China Scholarship Council.


1488O – Liu Q, Adami H-O, Reichenberg A, et al. Cancer risk in individuals with intellectual disability. ESMO Congress 2021 (16-21 September).