BACKGROUND: Hurthle cell carcinoma (HCC) is an uncommon and more aggressive thyroid cancer. To date, there is a paucity of data at a population level. In this study, demographic, clinical, and pathologic characteristics of HCC were investigated and compared with other types of differentiated thyroid cancers (ODTCs). The authors also evaluated disease‐specific survival and compliance with American Thyroid Association (ATA) management guidelines from 2009. METHODS: The Surveillance, Epidemiology, and End Results (SEER) database from 1988 to 2009 was used to obtain data on patients with thyroid cancer. Data analyses were performed using chi‐square tests, analysis of variance, Kaplan‐Meier analysis, binary logistic regression, and Cox proportional hazards regression. RESULTS: In total, 3311 patients with HCC and 59,585 patients with ODTC were identified. Compared with ODTC, HCC was more common among men (31.1% vs 23.0% for ODTC; P < .001) and among older patients (mean age, 57.6 years vs 48.9 years for ODTC; P < .001). Patients with HCC presented with higher SEER disease stage (P < .001), and their tumors were larger (36.1 mm vs 20.2 mm for ODTC; P < .001). Fewer patients underwent total thyroidectomy (P = .028). Both overall and disease‐specific survival were lower for patients with HCC (P < .001), and neither improved over the last 2 decades (P = .689). After adjustment, age ≥45 years, not undergoing surgery, and metastatic disease were strongly associated with a worse prognosis (hazard ratio >3.0). Compliance with recommended surgical treatment according to ATA guidelines was lower among patients with HCC aged ≥65 years (odds ratio [OR], 1.43; P = .002) and among unmarried patients (OR, 1.29; P = .004). Predictors of noncompliance with ATA guidelines for treatment with radioactive implants or radioisotopes were age ≥65 years (OR, 1.31; P = .017), diagnosis between 1988 and 1997, no surgery, and partial thyroidectomy (OR, 1.81, 19.48, and 4.02, respectively; P < .001). CONCLUSIONS: HCC has more aggressive behavior and compromised survival compared with ODTC. The current results indicated that it may be important to consider a different staging system or separate practice guidelines. Cancer 2013. © 2012 American Cancer Society.

BACKGROUND: Medullary thyroid microcarcinomas (microMTCs) are medullary thyroid carcinomas (MTCs) that measure 1 cm in size for which there is a paucity of data on incidence, characteristics, and clinical significance. METHODS: Patients who had a diagnosis of microMTC were abstracted from the Surveillance, Epidemiology, and End Results database (1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007). The data were analyzed using chi-square tests, t tests, and log-rank tests; multivariate logistic regression was used to identify factors that were associated independently with lymph node metastases. Tests for diagnostic accuracy, including likelihood ratio tests and post-test probability tests, were computed to evaluate the size-specific likelihood of developing lymph node metastases among patients with microMTC. RESULTS: In total, 310 patients had microMTC; its incidence increased during the study period (P trend ¼ .033), and microMTC as a proportion of all MTCs increased by 39%. The mean tumor size was 5.7 mm. Thirty-one percent of tumors were multifocal, and 7.8% had extrathyroid extension. Lymph node metastases occurred in nearly 37% of patients who had any lymph nodes removed (65 of 176 patients). Nearly 20% of patients had regional disease, and 5% had distant metastases. The overall 10-year survival rates for patients with localized, regional, and distant disease stages were 96%, 87%, and 50%, respectively (P < .001). After adjustment, extrathyroid extension (odds ratio [OR], 41.9; P < .001) and tumor size (OR, 1.2; P ¼ .008) retained an independent association with lymph node metastases. MTCs that measured 5 mm were associated with a probability of lymph node metastases of approximately 23%, and the probability increased for patients who had tumors >5 mm. CONCLUSIONS: The current results indicated that microMTCs have significant rates of poor prognostic features known to impact the survival of patients with MTC. These microcarcinomas are an important clinical entity that requires comprehensive evaluation and surgical management. Cancer 2012;118:620-

BACKGROUND: Insular thyroid cancer (ITC) is an uncommon, poorly differentiated thyroid malignancy. To date, there have been no population-level studies of the characteristics and outcomes of patients with ITC. METHODS: The authors used the Surveillance, Epidemiology, and End Results (SEER) database from 1999 to 2007 to compare the characteristics and prognosis of patients who had ITC with those of patients who had well differentiated thyroid cancer (WDTC) and anaplastic thyroid cancer (ATC). Data analyses were performed using chi-square tests, analyses of variance, log-rank tests, and multivariate regression. RESULTS: There were 114 patients with ITC, 497 patients with ATC, and 34,021 patients with WDTC. The mean age of patients with ITC was 62.1 years versus 48.1 years for patients with WDTC and 69.5 years for patients with ATC (P < .001). The mean ITC tumor size was 5.9 cm versus 2.0 cm for WDTC and 6.4 cm for ATC (P < .001). Distant metastasis occurred in 31% of patients with ITC versus 4.5% of patients with WDTC and 59.1% of patients with ATC (P < .001). Insular histology was associated independently with compromised survival in the overall study sample (hazard ratio [HR], 2.1; P ¼ .001). The 5-year disease-specific survival rate was 72.6%, 97.2%, and 9.1% for patients with ITC, WDTC, and ATC, respectively (P < .001). After adjustment, radioiodine therapy (HR, 0.15; 95% confidence interval, 0.04-0.5) and distant metastasis (HR, 15.3; 95% confidence interval, 3.7-62.2) were associated independently with ITC survival. The mortality rate was 7.1%, 12%, and 54.3% for patients with localized, regional, and distant stage ITC, respectively (P < .001). For patients who had ITC with distant metastasis, thyroidectomy and radioiodine therapy independently improved survival. CONCLUSIONS: ITC is rare and aggressive. The current results indicated that its treatment should include total thyroidectomy and high-dose radioiodine for all patients and neck dissections for patients with lymph node disease. Early diagnosis and close surveillance are essential in the management of patients with ITC. Cancer 2012;118:3260-7.