RT Book, Section A1 Ruan, Daniel T. A1 Clark, Orlo H. A2 Morita, Shane Y. A2 Dackiw, Alan P. B. A2 Zeiger, Martha A. SR Print(0) ID 6162678 T1 Chapter 7. Anaplastic Thyroid Carcinoma, Metastases to the Thyroid Gland, and Thyroid Lymphoma T2 McGraw-Hill Manual: Endocrine Surgery YR 2010 FD 2010 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-160645-5 LK accesssurgery.mhmedical.com/content.aspx?aid=6162678 RD 2024/03/28 AB Anaplastic thyroid cancer (ATC) is a highly aggressive malignancy that accounts for more than 39% of all thyroid cancer deaths even though it represents less than 2% of all thyroid cancers diagnosed.1,2 Although the incidence of well-differentiated thyroid cancer (WDTC) has increased in recent years, newly diagnosed ATC is decreasing in the United States. This may be because of improvements in histologic techniques, the elimination of endemic goiter, or advances in the treatment of patients with WDTC.3 It is possible that a significant proportion of thyroid lymphomas, medullary thyroid carcinomas (MDCs), and other non-ATC were misdiagnosed as ATC in the past; histologic accuracy has benefited from developments in immunohistochemistry (Figure 7-1).4 Because ATC is associated with WDTC in more than 80% of cases, earlier removal of WDTC could, in theory, reduce anaplastic transformation and ATC incidence.5,6 Conversely, incomplete or delayed therapy for patients with WDTC increases the risk of anaplastic transformation.7