Cancers and immune related diseases associated with Down's syndrome: a record linkage study.

OBJECTIVE

To determine the risk of cancers and selected immune related diseases in people with Down's syndrome, relative to risk in other people.

DESIGN

Cohort analysis of a linked dataset of abstracts of hospital and death records; results expressed as the ratios of rates of disease in people with and without Down's syndrome.

SETTING

The former Oxford health region, England, 1963-1999.

SUBJECTS

Cohort of 1453 people with Down's syndrome and cohort of 460,000 people with other conditions for comparison.

MAIN OUTCOMES

As expected, the rate ratio for leukaemia was substantially elevated in people with Down's syndrome: it was 19-fold higher (95% confidence intervals 10.4 to 31.5) than the rate in the comparison cohort. For other cancers combined, excluding leukaemia, the rate ratio was not significantly elevated (1.2; 0.6 to 2.2). The risk of testicular cancer was increased (12.0; 2.5 to 35.6), although this was based on only three cases in the cohort of subjects with Down's syndrome. Significantly elevated risks were found for coeliac disease (4.7; 1.3 to 12.2), acquired hypothyroidism (9.4; 3.4, 20.5), other thyroid disorders, and type 1 diabetes mellitus (2.8; 1.0 to 6.1). A decreased risk was found for asthma (0.4; 0.2 to 0.6).

CONCLUSIONS

Our data add to the body of information on the risks of co-morbidity in people with Down's syndrome. The finding on asthma needs to be confirmed or refuted by other studies.