1. Survivors of childhood cancer had a significantly increased risk of developing certain types of autoimmune diseases later in life.
Evidence rating level: 2 (Good)
Study Rundown: Recent advances in the diagnosis and treatment of childhood cancers have led to dramatic decreases in mortality. As a larger number of children with cancer now survive into adulthood, there is an increased focus on understanding the potential long-term complications of their disease and treatment. Previous studies have demonstrated long lasting abnormalities in the immune function of patients who received chemotherapy and radiation. This study followed childhood cancer survivors in Scandinavia to analyze changes in the lifetime risk of autoimmune diseases. Among patients diagnosed with cancer before the age of 20, there was a significant increase in the rate of hospitalization for autoimmune diseases. The risk of acquiring a variety of autoimmune diseases was increased, including those with systemic involvement (e.g. Sjogren’s syndrome), with organ involvement (e.g. Addison disease and type-1 diabetes mellitus), and without detectable autoantibodies (e.g. sarcoidosis). The cancers most likely to result in increased autoimmune diseases were leukemia, Hodgkin’s lymphoma, renal cancers, and CNS tumors. Though this study did not assess the effects of different treatment modalities and may have suffered from a degree of ascertainment bias, it shows conclusively that childhood cancer is associated with development of autoimmune diseases.
Relevant Reading: Chronic health conditions in adult survivors of childhood cancer
In-Depth [case-control study]: This large case-control study utilized patient data from national cancer registries and national population health archives in Denmark, Iceland, and Sweden to assess the link between childhood cancer and the development of autoimmune disease later in life. In all, 25,635 individuals diagnosed with cancer before the age of 20 were compared with 128,023 healthy controls and followed for a total of 2,765,561 person-years. The standardized hospitalization rate ratio for autoimmune disease was significantly increased among childhood cancer survivors (1.4, 95% CI: 1.3 – 1.5) as was the absolute excess risk (67 cases per 100,000 person-years). The significant increase in autoimmune diseases was led by type-1 diabetes mellitus (absolute excess risk 23), Addison’s disease (13), Hashimoto’s thyroiditis (9), sarcoidosis (7), chronic rheumatic heart disease (6), ITP (6), autoimmune hemolytic anemia (3), Sjogren’s syndrome (2), localized scleroderma (2), pernicious anemia (1), and polyarteritis nodosa (1). The cancers most associated with increased autoimmune diseases were leukemia (RR 1.6), Hodgkin’s lymphoma (1.6), renal cancer (1.6), and CNS tumors (1.4). Though the relative risk for increased autoimmune diseases was constant over the median 15 years of follow-up, the effect was greatest within the first 5 years after cancer diagnosis.
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