Patients with chronic autoimmune thyroiditis are not at higher risk for developing clinically overt thyroid cancer: a 10-year follow-up study

Abstract

<jats:p>Objective </jats:p> <jats:p>The association between chronic autoimmune thyroiditis (CAT) and differentiated thyroid cancer (DTC) remains controversial. The incidence of DTC increases when screening procedures are implemented, as typically occurs in CAT patients being routinely submitted to thyroid Ultrasound (US). The aim of this study was to longitudinally evaluate the long-term development of DTC in patients with CAT. </jats:p> <jats:p>Design and Methods </jats:p> <jats:p>A retrospective longitudinal cohort study was designed. 510 patients with chronic autoimmune thyroiditis (CAT) with a 10-years follow-up were enrolled. Patients were divided in two groups according to the presence (CAT+NOD+; n=115) or absence (CAT+NOD-; n=395) of co-existent nodules at diagnosis. The main outcome measures were appearance of new thyroid-nodules and development of DTC during follow-up. </jats:p> <jats:p>Results: During a 10-years median follow-up period, new thyroid-nodules were detected in 34/115 (29.5%) patients in the CAT+NOD+ group and in 41/395 (10.3%) in the CAT+NOD- group (p&lt;0.001). Logistic regression analysis showed that thyroid-volume at diagnosis and belonging to the CAT+NOD+ group significantly predicted the appearance of a new thyroid nodule during follow-up, independently of baseline age and sex. Among the 75 patients experiencing the appearance of a new nodule, 27 (39%) met the criteria for fine-needle-aspiration-cytology (FNAC). A benign cytological diagnosis was rendered in all cases </jats:p> <jats:p>Conclusions: In our series of CAT patients the appearance of new thyroid-nodules was frequent, but none of them was found to be malignant. The presence of CAT appears to be associated with a negligible risk of developing clinically overt DTC. </jats:p>

Hashimoto Thyroiditis and Thyroid Ultrasound: A Prospective Study

“…Also, they were more recently reassessed in several studies conducted in consecutive patients submitted to FNA, who are believed to be less subject to potential selection bias of surgical series [35]. However, according to FNA studies, the link between PTC and HT seems less evident [18,46] Rotondi et al [19] in a 10 year follow-up study of 510 patients with CAT, who presented a negligible risk of developing thyroid carcinoma nodules.…”

“…Some reports describe a higher prevalence of benign nodules in HTthan in the general population, which is usually attributed to stimulating factors such as TSH, IGF1, and local cytokines. However, there is still controversy whether CAT predisposes to malignancy [17][18][19].…”

The Immune Landscape of Papillary Thyroid Cancer in the Context of Autoimmune Thyroiditis

“…Autoimmune thyroiditis, also known as Hashimoto thyroiditis, was first considered as a risk factor for PTC in 1955 [ 7 ], along with a family history of PTC [ 8 ], therapeutic and diagnostic irradiation [ 5 ], and inadequate dietary intake of iodine [ 9 ]. After the initial 1955 report [ 7 ], several studies have examined the PTC-thyroiditis association (summarized in Table 1 ), especially after the introduction of cancer immunotherapy to the clinical practice [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ].…”

“…Scholars have long debated whether this association represents the coexistence of two independent but common diseases that are brought together by the increased use of thyroid ultrasound and fine-needle aspiration, or if it instead reflects a true cause–effect relationship [ 10 , 11 , 12 , 13 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Some studies have suggested that thyroiditis attenuates PTC severity [ 12 , 13 , 20 , 24 , 25 , 29 , 30 , 31 ], while others have concluded that thyroiditis promotes the progression of PTC [ 10 , 17 , 18 , 19 , 32 ]. Recently, McLeod et al [ 32 ] conducted a case-control study nested within the United States Army personnel who served between 1996 and 2014.…”

Cancer Risk in Hashimoto’s Thyroiditis: a Systematic Review and Meta-Analysis

“…Consistent with this, some studies show that HT and the occurrence of thyroid cancer have a strong correlation ( 10 , 11 ). Unlike this, several studies indicate that HT is not associated with the development of thyroid cancer and breast cancer ( 12 , 13 ). Given conflicting evidence and newly added epidemiological studies, we conducted a meta-study to examine and assess the association between HT and cancer.…”