LITTLE FALLS, N.J., July 13 — The increasing incidence of thyroid cancer in the U.S. is more than the result of better screening, researchers said.

• Explain that incidence rates of thyroid cancer increased among tumors of all sizes — not just the smallest ones, which would be expected if the increase was attributable to increased screening alone.
• Note that the researchers call for the investigation of other potential explanations, including diet, environmental influences, and molecular pathways.

Incidence rates rose for tumors of all sizes — not just the smallest ones, as it would if more cases were simply being caught by increased screening, Amy Y. Chen, MD, MPH, and colleagues reported online in Cancer.

“Our finding that even the largest tumors and tumors with distant spread of disease had an increasing incidence suggests that other reasons for this increase, including environmental, dietary, and genetic causes, need to be explored,” the researchers said.

Previous studies have found an increasing incidence of thyroid cancer, and some researchers have pointed to increased detection through more widespread and aggressive use of ultrasound and image-guided biopsy.

But increasing incidence rates can also reflect a true increase in the number of cancers, the researchers said.

So, to determine potential causes of the increase, researchers looked at data on 30,766 thyroid cancer patients from the Surveillance, Epidemiology, and End Results (SEER) study. All were diagnosed between 1988 and 2005.

Mortality rates were unchanged over that period, despite higher rates of diagnosis, the researchers said.

Among women, incidence of thyroid cancer increased from 6.4 per 100,000 to 14.9 per 100,000, while incidence among men increased from 2.5 per 100,000 to 5.1 per 100,000.

Although the highest rate of increase was for tumors under 1 cm (P<0.001), there were significant increases in all tumor sizes, particularly those greater than 4 cm, they noted.

The researchers reported no conflicts of interest.

Primary source: Cancer

Source reference:
Chen AY, et al “Increasing incidence of differentiated thyroid cancer in the United States, 1988-2005″ Cancer 2009; DOI: 10.1002/cncr.24416.

No Comments »

No comments yet.

RSS feed for comments on this post. TrackBack URL

Leave a comment

You must be logged in to post a comment.