Studies have reported an increasing incidence of thyroid cancer since 1980. One possible explanation for this trend is increased detection through more widespread and aggressive use of screening tests. Researchers at the American Cancer Society analyzed thyroid cancer incidence between 1988 and 2005 using the National Cancer Institute's (NCI's) Surveillance Epidemiology and End Results (SEER) dataset.

They found incidence rates increased for all sizes of tumors, suggesting that screening is not the only explanation for the rise. The highest rate of increase was for primary tumors smaller than 1.0 cm, which rose nearly 10 percent per year among men from 1997 and 2005, and nearly 9 percent/year from 1988 to 2005 among women. Incidence of tumors 4 cm or larger increased more than 3.5 percent per year from 1988 to 2005 among men and 5.7 percent per year from 1988 to 2005 among women.

The authors conclude that incidence rates of differentiated thyroid cancers of all sizes increased between 1988 and 2005 in both men and women, and that the increased incidence across all tumor sizes suggests that increased detection through testing is not the sole explanation. Other explanations, including environmental influences and molecular pathways, should be investigated.

Article:

"Increasing Incidence of Differentiated Thyroid Cancer in the US (1988-2005)."
Amy. Y. Chen, Ahmedin Jemal, and Elizabeth M. Ward.
CANCER; Published Online: July 13, 2009 (DOI: 10.1002/cncr.24416); Print Issue Date: August 15, 2009

Source
American Cancer Society