Increasing Incidence of Adult Thyroid Cancers in Florida (1981-2009)

Background: The incidence of thyroid cancer has increased continuously and sharply over the past decade. This study reports the trend of thyroid cancer incidence from 1981 to 2009 in the Florida adult population by race, ethnicity, age, stage, histology and tumor size between males and females to identify possible factors related to thyroid cancers.

Methods: We analyzed all patients who are adult (≥18yrs), Florida residents excluding those diagnosed with carcinoma in situ as primary tumor site in the Florida Cancer Data System (FCDS). Incidence per 100,000 people for each gender was age-adjusted by using the 2000 US standard population.

Results: From 1981 to 2009, 8,246 male and 22,696 female Floridian adults were diagnosed with thyroid cancer. Thyroid cancer incidence in men was White (92.3%), Black (4.6%), Non-Hispanic (84.9%), Hispanic (13.4%), age 18-49 (35.5%), 50-69 (43.3%), 70 or older (21.3%) and papillary thyroid cancer (84.8%). For women, the incidence rates were White (88.1%), Black (8.1%), Non-Hispanic (81.2%), Hispanic (17.4%), age 18-49 (51.3%), 50-69 (34.0%), 70 or older (14.7%) and papillary thyroid cancer (90.2%). There was a significant increase in thyroid cancer incidence from 1981 to 2009. Compared to baseline 3-year rolling age-adjusted incidence rate in 1981-1983 in males and females, respectively, the overall rate in 2007-2009 increased (323% and 471%) as well as for papillary thyroid cancer (355% and 555%), Whites (335% and 469%), Blacks (158% and 355%), localized (352% and 577%) and distant stages (67% and 44%), different age groups (18-49yrs: 253% and 479%; 50-69yrs: 340% and 640%; age 70 or older: 433% and 279%) and tumor size (30mm or larger: 169% and 173%; 17-29mm: 272% and 242%; 9-16mm: 332% and 414%; less than 9mm: 55% and 109%)

Conclusions: In Floridian adults, age-adjusted thyroid carcinoma incidence rates are increasing variably across different races, ethnicities, age groups, stage, histology, and tumor size. The greatest increases in incidences were associated with tumor size in both genders. The incidence rate in larger tumor size (>30mm) is tripled than the increasing rate of smaller tumor size (<9mm) which indicated that there are other factors, not due solely to improved detection contributed to the increasing incidence rate of thyroid cancer.