Abstract
Objective
The prevalence and clinical significance of incidental differentiated thyroid cancer (DTC) in patients with Graves’ disease (GD) remain uncertain. Thyroid stimulating antibody (TSI Ab)-titers were thought to be responsible for the potentially increased incidence or aggressiveness of PTC in that setting. The aim of this study was to compare the prevalence of incidental DTC among patients with GD and euthyroid goiter (EG), to assess the ability of TSI to predict DTC in GD and to investigate the clinical features that may predict incidental DTC in GD and EG.
Methods
Two hundred and forty eight patients with EG and 245 patients with GD patients who had undergone total thyroidectomy at our institution between 2005 and 2013 were retrospectively selected from our data base. An analysis of incidentally discovered DTC was conducted comparing GD group with EG group.
Results
Incidental micro-papillary thyroid cancer (MPTC) was found in 28% in EG group, as compared to 26% in GD group. PTC Patients with GD were significantly younger (44 vs 59) and less likely to have compressive symptoms than with EG before surgery (p < 0.001). In GD group, patients with MPTC were also significantly older (p = 0.009) than those without, were more likely to have symptomatic goiter (p < 0.001), and to have a nodular disease (p < 0.001). TSI ab titer did not predict MPTC in GD group (The AUC curve was 0.55 (95% CI: 0.46, 0.64). Among patients with GD and incidental MPTC, 58% of patients had at least one nodule.
Conclusion
The prevalence of incidental DTC in GD is comparable to EG. Each is increased compared to general population. Age of presentation of PTC was significantly lower in GD suggesting an increased risk for MPTC in GD. Nodule size greater than 1 cm predicted incidental DTC whereas TSI ab titers and disease duration did not.
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Introduction
Graves’ disease (GD) comprises 50% to 80% of hyperthyroidism cases . Management of GD depends on clinical judgment of the physician and personal preference and values of the patients . Treatment guidelines recommend surgical approach when differentiated thyroid cancer (DTC) is documented or suspected . There remains controversy surrounding the risk and prognosis of DTC in GD. Historically, GD was first claimed to protect against DTC , however not long after new studies refuted this hypothesis . Many studies reported increased prevalence and aggressiveness of incidental thyroid cancers in GD, causing lymph node, regional and even distal metastasis even with small tumor while others questioned the clinical relevance of incidental thyroid cancer, suggesting that this finding was only a selection bias . Recently a large cohort study using national database reported higher incidences of both TC and other types of cancers in patients with GD increasing the controversy further . Another recent study showed increased mortality in non-occult PTC. Moreover, some investigators have strongly suggested that the thyroid-stimulating antibodies could stimulate a malignant focus resulting in more aggressive behavior in TC .
The aim of this study was to determine the prevalence and aggressiveness of incidental thyroid carcinoma diagnosed in patients undergoing total thyroidectomy (TT) for GD and to compare the results with patients who underwent TT for nontoxic (euthyroid) goiter (EG). We also assessed the ability of thyroid receptor stimulating antibodies (TSI ab) to predict DTC in GD using receiver operating characteristic (ROC) curves.
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