Small tumors in adults over age 45 become most common form of papillary thyroid cancer

Data from the National Cancer Institute (NCI) have shown that the most common form of papillary thyroid cancer is now microcarcinomas occurring in adults over the age of 45.

A study published in the journal Thyroid reached this conclusion after analyzing data collected in the NCI's Surveillance, Epidemiology, and End Results (SEER) 17 Registries Database.

Previously, papillary thyroid cancer was thought to occur relatively often among adults under the age of 45, as evidenced by information to that effect on the NCI's official website.

However, information culled from the SEER database indicates that the average age at which papillary thyroid cancer develops has been steadily increasing since 1973. In that year, 60 percent of all cases of the disease occurred in patients under age 45, the study specifies.

That figure gradually shifted, so that by the year 2000 more individuals were being diagnosed with papillary carcinomas during or after their 45th year than before. By 2006, more than 60 percent of these tumors occurred in individuals over that age, researchers noted.

Another notable shift in papillary thyroid cancer diagnoses is the size at which thyroid gland tumors are detected.

The new study notes that the largest increase in reported papillary carcinomas occurred among those of the smallest size, less than 1 centimeter across. While the detection of tumors of all sizes has increased in the past three decades, these so-called microcarcinomas have begun to account for more and more of the total number of diagnoses, especially among patients over 45.

The authors said that in individuals of this age range, these so-called microcarcinomas accounted for 43 percent of all diagnoses of papillary thyroid cancer in 2003, compared to the 34 percent of diagnoses related to micro-tumors in those under 45.

Researchers concluded that the increasing use of medical imaging technology is resulting in the discovery of small thyroid nodules among mature Americans whose thyroid tumors might otherwise never be noticed.

Papillary carcinomas account for at least 70 percent of the 45,000 thyroid cancer diagnoses made every year in the U.S., according to the NCI.