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Survivors of childhood cancers at increased risk for autoimmune diseases


 

FROM ANNALS OF RHEUMATIC DISEASES

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Analysis of cancer registry data from Denmark, Iceland, and Sweden over more than 60 years found that survivors of childhood cancer had a 1.4-fold higher risk of autoimmune disease compared with matched controls.

Results showed significantly increased rates of hospital visits for 11 of 33 autoimmune diseases investigated. The most prominent excesses were for insulin-dependent diabetes mellitus, Addison’s disease, and Hashimoto’s thyroiditis, accounting for more than half the total number of excess autoimmune cases (Ann Rheum Dis 2015 Nov 6. doi: 10.1136/annrheumdis-2015-207659). The investigators could not rule out the influence of surveillance bias, given that hospitalization rate ratios were highest in the first 5 years after cancer diagnosis, potentially a consequence of closer surveillance during that period. For most autoimmune diseases, however, the excess risk persisted through the second and third decades after cancer diagnosis.

The Nordic childhood cancer survivor cohort comprised 25,635 individuals diagnosed with cancer before the age of 20 years, from the 1940s-1950s (start of cancer registries in Denmark, Iceland, and Sweden) to 2008. Expected autoimmune disease rates were based on rates of hospital visits for the comparison cohort, which included 128,023 individuals matched for age, sex, and country of the corresponding survivor. The standardized hospitalization rate ratio is the observed number of autoimmune diseases among survivors divided by the expected rate. Childhood malignancies with the most pronounced risk increases were leukemia (standardized hospitalization rate ratio, 1.6), Hodgkin lymphoma (1.6), renal tumors (1.6), and central nervous system neoplasms (1.4).

“Cure is no longer a sufficient goal in childhood cancer care. As the vast majority of these patients survive, attention must be to paid to their long-term quality of life and health challenges,” wrote Dr. Anna Salifors Holmqvist of the department of clinical sciences, pediatric oncology and hematology, Skane University Hospital, Lund University, Sweden.

Increased risks were noted for a wide range of relatively rare autoimmune diseases after treatment for several types of childhood malignancies, and underlying mechanisms should be addressed in future studies, noted Dr. Holmqvist and her colleagues.

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