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Autoimmune thyroiditis linked to increased risk of thyroid cancer in children

Autoimmune thyroiditis in children with thyroid nodules has been found to be independently linked to an increased risk of thyroid cancer

Children with autoimmune thyroiditis and thyroid nodules is independently associated with a higher risk of thyroid cancer according to the findings of a cross-sectional study by US researchers based at Harvard Medical School, US.

Autoimmune thyroiditis (AIT) is characterised by the presence of thyroid autoantibodies in serum and is the most common cause of thyroid disorder among children and adolescents although it is mostly asymptomatic. AIT, which is also known as Hashimoto’s thyroiditis, is frequently associated with papillary thyroid cancer and may indeed be a risk factor for developing the cancer. Nevertheless, the jury is still out as other work suggests that a correlation between AIT and a higher incidence of thyroid cancer is still undefined. In children there is also some uncertainty over this relationship. For instance, some data suggests AIT seems to influence the development of thyroid nodules, but not cancer , whereas other data indicates a relationship with malignancy. Whilst the presence of thyroid nodules are more common in children with AIT, whether this ultimately increases the risk of thyroid cancer is unclear although there is a clear relationship between the presence of AIT, nodules and malignancy in adults.

In the present study, the US researchers sought to better understand the relationship between AIT in children and thyroid cancer, among a cohort who underwent thyroid nodule evaluation over an extended period of time. Included participants were < 19 years of age and who had undergone fine needle aspiration of a nodule between 1998 and 2020. The presence of thyroid cancer was defined by histopathology for resected nodules and the researchers set the primary outcome as the presence of thyroid cancer.

Autoimmune thyroiditis and cancer in children

A total of 385 individuals with a mean age of 15.5 years (81% female) with 458 nodules, were included in the retrospective analysis.

Thyroid cancer was present in 108 nodules (24%) and AIT was seen 95 (25%) of the overall study population. The most common type of thyroid cancer was papillary (82%) followed by follicular carcinoma (14%).

The presence of clinical AIT was independently associated with an increased risk of thyroid cancer (odds ratio, OR = 2.19, 95% CI 1.32 – 3.62). Moreover, thyroid cancer was directly associated with the diameter of the nodules (OR = 1.05, 95% CI 1.03 – 1.06, p < 0.001) and inversely associated with age (OR = 0.90, 95% CI 0.83 – 0.97, p = 0.007). Interestingly, female sex and the presence of multiple nodules were both independently associated with a lower risk of thyroid cancer.

The authors concluded that among children with thyroid nodules, the presence of AIT was associated with an increased risk of thyroid cancer. They suggested that a clinical diagnosis of AIT may inform the assessment of thyroid cancer risk and surgical decision-making in children who had thyroid nodules.

Keefe G et al. Autoimmune Thyroiditis and Risk of Malignancy in Children with Thyroid Nodules Thyroid 2022

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