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Changing Incidence of Thyroid Cancer

Changing Incidence of Thyroid Cancer To the Editor: In their study of the increasing incidence of thyroid cancer in the United States between 1973 and 2002, Drs Davies and Welch1 concluded that the increase was artifactual, due to increasing detection of small thyroid nodules. We believe that this conclusion is premature. Use of imaging technology for the thyroid may have begun increasing in the early 1980s, but workup for thyroid disease generally occurs because of symptoms or signs. We are not aware of any organized, concerted, sustained effort in thyroid cancer screening. Davies and Welch observed the greatest increase in incidence for cancers less than 1 cm in diameter, but they show that tumors of 1 to 2 cm and 2 to 5 cm in diameter have also been strongly increasing in incidence. Nodules about 1 cm in diameter are detectable by palpation, and those 2 to 5 cm in diameter are frequently visually apparent and unlikely to be undetected or to be observed clinically but not worked up for cancer. If incidence of thyroid cancer were indeed increasing, with modern diagnostic technology most tumors would be detected near the smallest sizes detectable with palpation. Thus, the increase in incidence of small- to medium-sized cancers is just as consistent with a true increase in disease incidence as with increasing detection of existing subclinical tumors. We believe that the reasoning concerning thyroid mortality used by Davies and Welch involves weak evidence. Back to top Article Information Financial Disclosures: None reported. References 1. Davies L, Welch HG. Increasing incidence of thyroid cancer in the United States, 1973-2002. JAMA. 2006;295:2164-216716684987Google ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA American Medical Association

Changing Incidence of Thyroid Cancer

JAMA , Volume 296 (11) – Sep 20, 2006

Changing Incidence of Thyroid Cancer

Abstract

To the Editor: In their study of the increasing incidence of thyroid cancer in the United States between 1973 and 2002, Drs Davies and Welch1 concluded that the increase was artifactual, due to increasing detection of small thyroid nodules. We believe that this conclusion is premature. Use of imaging technology for the thyroid may have begun increasing in the early 1980s, but workup for thyroid disease generally occurs because of symptoms or signs. We are not aware of any organized,...
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Publisher
American Medical Association
Copyright
Copyright © 2006 American Medical Association. All Rights Reserved.
ISSN
0098-7484
eISSN
1538-3598
DOI
10.1001/jama.296.11.1350-a
Publisher site
See Article on Publisher Site

Abstract

To the Editor: In their study of the increasing incidence of thyroid cancer in the United States between 1973 and 2002, Drs Davies and Welch1 concluded that the increase was artifactual, due to increasing detection of small thyroid nodules. We believe that this conclusion is premature. Use of imaging technology for the thyroid may have begun increasing in the early 1980s, but workup for thyroid disease generally occurs because of symptoms or signs. We are not aware of any organized, concerted, sustained effort in thyroid cancer screening. Davies and Welch observed the greatest increase in incidence for cancers less than 1 cm in diameter, but they show that tumors of 1 to 2 cm and 2 to 5 cm in diameter have also been strongly increasing in incidence. Nodules about 1 cm in diameter are detectable by palpation, and those 2 to 5 cm in diameter are frequently visually apparent and unlikely to be undetected or to be observed clinically but not worked up for cancer. If incidence of thyroid cancer were indeed increasing, with modern diagnostic technology most tumors would be detected near the smallest sizes detectable with palpation. Thus, the increase in incidence of small- to medium-sized cancers is just as consistent with a true increase in disease incidence as with increasing detection of existing subclinical tumors. We believe that the reasoning concerning thyroid mortality used by Davies and Welch involves weak evidence. Back to top Article Information Financial Disclosures: None reported. References 1. Davies L, Welch HG. Increasing incidence of thyroid cancer in the United States, 1973-2002. JAMA. 2006;295:2164-216716684987Google ScholarCrossref

Journal

JAMAAmerican Medical Association

Published: Sep 20, 2006

References