Abstract
Background Recently, several studies have reported that dedifferentiation occurs in fatal well-differentiated thyroid cancer (WDTC) cases. This study aimed at investigating the clinicopathological characteristics of WDTC undergoing dedifferentiation. Methods A total of 63 WDTC patients harboring dedifferentiated phenotype were enrolled in the study. The Kaplan-Meier method and Cox regression analysis were used to perform survival analyses. Harrell index of concordance (C-index) and Akaike information criterion (AIC) were calculated to compare the predictive value for prognosis among several prognostic classification systems. Results The median cause-specific survival (CSS) of patients was 138 months, with the CSS rate of 64.0% and 53.3% at 5 and 10 years, respectively. Presence of the anaplastic thyroid cancer (ATC) phenotype significantly increased the risk of poor CSS (P = 0.033), and age was the only independent risk factor for disease progression (P = 0.015). The C-index and AIC of the age, grade, extent, size (AGES) prognostic classification system for the CSS were 0.723 and 59.937, respectively. Conclusions The presence of dedifferentiated phenotypes can be responsible for the poor outcomes in WDTC patients. The AGES system demonstrates to be an optimal prognostic system for WDTC undergoing dedifferentiation.
Highlights
In the United States, thyroid cancer has become the fifth most common cancer expected to occur in women in 2017 [1]
Almost the entire change has been attributed to the rapid increase in incidence of well-differentiated thyroid cancer (WDTC), which comprises the vast majority (>90%) of all thyroid cancers [1, 3, 4], including papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC)
We have found a cohort of WDTC patients harboring poorly differentiated thyroid cancer (PDTC)/anaplastic thyroid cancer (ATC) at Fudan University Shanghai Cancer Center (FUSCC)
Summary
In the United States, thyroid cancer has become the fifth most common cancer expected to occur in women in 2017 [1]. Several studies have reported presence of poorly differentiated phenotypes in fatal WDTC cases [5,6,7]. Anaplastic thyroid cancer (ATC) is one of the most aggressive malignancies with a median survival of 5 months and near 100% mortality rate [8] while poorly differentiated thyroid cancer (PDTC) is associated with a 5-year survival rate of 40–70% [5, 9, 10]. Several studies have reported that dedifferentiation occurs in fatal well-differentiated thyroid cancer (WDTC) cases. Presence of the anaplastic thyroid cancer (ATC) phenotype significantly increased the risk of poor CSS (P = 0 033), and age was the only independent risk factor for disease progression (P = 0 015). The AGES system demonstrates to be an optimal prognostic system for WDTC undergoing dedifferentiation
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