Thyroid Autoimmunity and Thyroid Cancer: Review Focused on Cytological Studies

Abstract

The association between Hashimoto thyroiditis (HT) and papillary thyroid carcinoma (PTC) has been originally suggested by retrospective pathological studies and has recently been re-evaluated and proposed on the basis of several fine-needle aspiration cytology (FNAC) studies. In FNAC studies, the association between HT and PTC is based on the comparison of anti-thyroid autoantibodies (ATA) (anti-thyroperoxidase [TPOAb] and anti-thyroglobulin [TgAb]), thyroid function (TSH), and cytology with histology of thyroid nodules and lymphocytic thyroid infiltration (LTI) of operated thyroid glands. Most of the pathological studies found a high prevalence rate of PTC in HT. In most FNAC studies, the risk ratio of PTC in HT patients was evaluated using multivariate statistical analysis: increased TSH levels represented the main and common independent risk factor of malignancy, although it resulted not consistently related to HT. On the other hand, several studies provided a positive relationship between ATA and PTC, particularly with TgAb. Two recent FNAC studies from the same referral center clearly demonstrated an independent risk for thyroid malignancy conferred by both TPOAb and TgAb, confirming the role of increased TSH levels, and found a significant association between PTC and ATA and diffuse LTI at histology. These studies are consistent with the hypothesis that autoimmune thyroid inflammation and increased serum TSH concentration may be involved in thyroid tumor growth. The complex relationship between HT and PTC, which involves immunological/hormonal pathogenic links, needs to be further investigated with prospective studies.

Differentiated thyroid cancer in children: Heterogeneity of predictive risk factors

“…. The role of other potential risk factors (iodine deficiency, Hashimoto thyroiditis) is still uncertain …”

“…7 The role of other potential risk factors (iodine deficiency, Hashimoto thyroiditis) is still uncertain. 8,9 As compared to DTCs occurring in adulthood, DTCs occurring in children/adolescents show significant clinical, pathological and also molecular differences, 10,11 and are characterized by a more aggressive phenotype and a more advanced stage at diagnosis, with a greater rate of regional lymph node involvement, extrathyroidal extension and even lung metastases. Nevertheless, DTCs occurring in children/adolescents are not associated with a higher mortality rate (less than 2% diseasespecific mortality in the long term) because the response to treatment and specifically to 131 I administration is excellent even when metastatic disease is present.…”

Papillary Thyroid Carcinoma Intertwined with Hashimoto’s Thyroiditis: An Intriguing Correlation

“…Lai et al [97] Range of mean rate of PTC among patients with HT: [104]. Nevertheless, the fear of the selection bias was abolished by the recent demonstration of a significant association of PTC with HT based on either pathological examination of surgical specimens or FNAB studies [60].…”

“…Thirdly, equivocal-favorable versus unfavorable-is the impact of HT on the prognosis of concurrent PTC [39][40][41][42][43][44][45][46][47][48]. Finally, the translation of the serum concentrations of thyroid autoantibodies [49-56] and thyroid-stimulating hormone (TSH) [55, [57][58][59][60][61][62][63] into predictive and prognostic PTC biomarkers incites a perpetual conflict.…”

“…Nevertheless, the demonstration of HT as a risk factor for PTC in univariate analysis while being a host-protective factor in multivariate analysis after controlling TSH levels should be mentioned [61]. Similarly, multivariate analysis showed that increased TSH levels were an independent risk factor of malignancy in most FNAB studies, albeit not consistently related to HT [60]. Consequently, the subclinical or overt hypothyroidism due to autoimmune destruction of thyroid-and not HT per se-could be the real culprit for the increased PTC risk in the context of HT.…”