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Thyroid cancer is rapidly increasing in incidence, but the mortality rate remains flat. Debate has arisen over the need to detect or treat most thyroid cancers early, given their favorable natural history. The appropriate extent of surgery for thyroid cancer is also controversial: some researchers advocate partial and others total thyroidectomy; some advocate prophylactic central cervical lymph node dissection, whereas others only rarely recommend lymphadenectomy. Although radioactive iodine is effective, its appropriate use and dosage remain controversial. In addition, molecular analysis of thyroid cancer is frequently used for diagnostic purposes involving preoperative fine-needle biopsy specimens as well as to define targetable pathways altered in the disease to guide clinical trials of drug therapy for advanced thyroid cancers.

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Despite being second only to the adrenal glands in terms of relative vascular perfusion, the thyroid gland is a rare site of metastatic disease; but when thyroid metastases occur, long-term survival has been reported to be dismal. To determine the incidence and management of isolated, metastatic disease to the thyroid, we reviewed our clinical experience. Between June 1986 and August 1994 ten patients underwent thyroidectomy for isolated, metastatic disease of nonthyroidal origin (mean +/- SD age 58 +/- 6 years, 30% female). The primary tumors were renal cell carcinomas (RCCs) (n = 5), esophageal adenocarcinoma (n = 1), pulmonary squamous cell carcinoma (n = 1), gastric leiomyosarcoma (n = 1), lingual squamous cell carcinoma (n = 1), and parotid gland carcinoma (n = 1). Three patients underwent preoperative fine-needle aspiration (FNA), all of which were suggestive of metastatic disease. The mean time from resection of the primary tumor to thyroid metastases was 3.5 +/- 6.0 years (range 0-19.5 years). Total thyroidectomy (n = 5) or lobectomy (n = 5) was performed without morbidity or mortality. After a median follow-up of 5.2 years six patients are alive and two are free of disease. Moreover, no patients have had recurrent disease in the neck. Thus carcinomas metastatic to the thyroid represent a rare cause of clinically significant thyroid disease, with RCCs comprising 50%. Most thyroid metastases (80%) present within 3 years of primary tumor resection, but with RCC they can occur as late as 19 years. The diagnosis of metastatic disease should be suspected in patients with even a remote history of cancer, especially RCC, and an FNA revealing clear cell or spindle cell carcinoma. Contrary to previous reports, long-term survival can be achieved after resection of the metastatic tumor. Furthermore, thyroidectomy may also palliate/prevent the potential morbidity of tumor recurrence in the neck.

Pediatric thyroid cancer is a rare disease with an excellent prognosis. Compared with adults, epithelial-derived differentiated thyroid cancer (DTC), which includes papillary and follicular thyroid cancer, presents at more advanced stages in children and is associated with higher rates of recurrence. Because of its uncommon occurrence, randomized trials have not been applied to test best-care options in children. Even in adults that have a 10-fold or higher incidence of thyroid cancer than children, few prospective trials have been executed to compare treatment approaches. We recognize that treatment recommendations have changed over the past few decades and will continue to do so. Respecting the aggressiveness of pediatric thyroid cancer, high recurrence rates, and the problems associated with decades of long-term follow-up, a premium should be placed on treatments that minimize risk of recurrence and the adverse effects of treatments and facilitate follow-up. We recommend that total thyroidectomy and central compartment lymph node dissection is the surgical procedure of choice for children with DTC if it can be performed by a high-volume thyroid surgeon. We recommend radioactive iodine therapy for remnant ablation or residual disease for most children with DTC. We recommend long-term follow-up because disease can recur decades after initial diagnosis and therapy. Considering the complexity of DTC management and the potential complications associated with therapy, it is essential that pediatric DTC be managed by physicians with expertise in this area.

Background: The incidence of thyroid cancer has increased at an alarming rate in both men and women in the United States. The etiology of this epidemic is unclear. We tested the hypothesis that a significant component of this epidemic is due to increased detection of occult disease. We examined whether the density of endocrinologists and general surgeons as well as employment of cervical ultrasonography were factors associated with this epidemic. Methods: Thyroid cancer incidence rates by states were obtained from the United States Cancer Statistics 1999-2009 reported by the National Program of Cancer Registries. The densities of endocrinologists and general surgeons and the employment of cervical ultrasonography were calculated on a statewide basis and correlated with the incidence of thyroid cancer. Results: Age-standardized incidence rates of thyroid cancer have increased in every state in the United States. Significant regional variations were noted, with the highest incidence rates in the northeast and the lowest in the south. The incidence rates were significantly correlated with the density of endocrinologists (r = 0.58, p < 0.0001 for males; r = 0.44, p = 0.0031 for females) and the employment of cervical ultrasonography (r = 0.40, p = 0.0091 for males; r = 0.36, p = 0.0197 for females). Both the density of endocrinologists and general surgeons and employment of cervical ultrasonography could explain 57% of the variability in state-level incidence for males and 49% for females. Conclusions: These data offer evidence to suggest that the epidemic of thyroid cancer is due to increased detection of a reservoir of previously occult disease. The increased detection of thyroid cancer results in therapeutic interventions including surgery and radioactive thyroid treatment that may be of limited benefit.

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The Bethesda 2007 Thyroid Cytology Classification defines follicular lesion of undetermined significance as a heterogeneous category of cases that are not convincingly benign nor sufficiently atypical for a diagnosis of follicular neoplasm or suspicious for malignancy. In our institution, we refer to these cases as indeterminate, and they are further sub-classified into two: (1) low cellularity with predominant microfollicular architecture and absence of colloid (IN(a)) and (2) nuclear features not characteristic of benign lesions (nuclear atypia) (IN(b)). We reviewed these indeterminate cases to document the follow-up trend using this two-tier classification. A search of the cytology records was performed for the period between January 2008 and June 2009. All thyroid fine-needle aspiration (FNA) cases were reviewed and the ones diagnosed as indeterminate were identified. Correlating follow-up FNA and/or surgical pathology reports were reviewed. The percentage of cases showing a malignancy was calculated. One hundred and seventy-one indeterminate cases were identified, representing 2.8% of the 6,205 thyroid FNA cases examined during the time under review (107 IN(a), 64 IN(b)). Records of follow-up procedures were available in 106 (61%) cases. Malignancy was identified in 27% of all indeterminate cases. This was disproportionately more in the IN(b) (56%) compared to the IN(a) (7%) cases. A diagnosis of "IN(a)" does not carry the same implication as that of "IN(b)". The IN(b) category needs a more aggressive follow-up than the IN(a) category and may justify an immediate referral for lobectomy. Despite the vague morphologic criteria for this diagnostic category, the indeterminate rate remains relatively low and falls within the NCI recommendation (<7%).