Abstract
Thyroid cancer (TC), the most common endocrine tumor, has steadily increased worldwide due to the increase of the papillary histotype. The reasons for this spread have not been established. In addition to more sensitive thyroid nodule screening, the effect of environmental factors cannot be excluded. Because high incidences of TC were found in volcanic areas (Hawaii and Iceland), a volcanic environment may play a role in the pathogenesis of TC. In January 2002, the Regional Register for TC was instituted in Sicily. With a population of approximately five million inhabitants with similar genetic and lifestyle features, the coexistence in Sicily of rural, urban, industrial, moderate-to-low iodine intake, and volcanic areas provides a conducive setting for assessing the environmental influences on the etiology of TC. In Sicily, between 2002 and 2004, 1,950 new cases of TC were identified, with an age-standardized rate (world) ASR(w) = 17.8/105 in females and 3.7/105 in males and a high female/male ratio (4.3:1.0). The incidence of TC was heterogeneous within Sicily. There were 2.3 times more cases in the Catania province (where most of the inhabitants live in the volcanic area of Mt. Etna): ASR(w) = 31.7/105 in females and 6.4/105 in males vs. 14.1 in females and 3.0 in males in the rest of Sicily. Multivariate analysis documented that residents in the volcanic area of Mt. Etna had a higher risk of TC, compared to the residents in urban, industrial, and iodine deficient areas of Sicily. An abnormally high concentration of several chemicals was found in the drinking water of the Mt. Etna aquifer, which provides water to most of the residents in the Catania province. Our data suggest that environmental carcinogen(s) of volcanic origin may promote papillary TC. Additional analyses, including cancer biological and molecular features, will allow a better understanding of risk factors and etiopathogenetic mechanisms.
Highlights
THYROID CANCER EPIDEMIOLOGY AND TREND Thyroid cancer (TC) is the most frequent endocrine neoplasm (Curado et al, 2007), which occurs two to four times more frequently in females than in males (Parkin et al, 2005)
We found a more than twofold increased incidence of TC in the province of Catania (ASRw F = 31.7/105; M = 6.4/105), where approximately 80% of the residents live in the volcanic area of Mt
M = 3.1/105; F = 8.1/105 M = 3.4/105; F = 9.5/105 M = 10.4/105; F = 71.4/105 M = 5.4/105; F = 37.4/105 M = 6.4/105; F = 31.7/105 PTC incidence crude rate = 9.0/105 vs. 6.2/105, respectively, in volcanic and non-volcanic area documented an increased amount of heavy metals in plants grown in volcanic areas
Summary
THYROID CANCER EPIDEMIOLOGY AND TREND Thyroid cancer (TC) is the most frequent endocrine neoplasm (Curado et al, 2007), which occurs two to four times more frequently in females than in males (Parkin et al, 2005). Its incidence has continuously increased worldwide in recent decades. This increase has occurred in many regions, with variable entity and independent of initial recorded levels, as indicated by data from population-based cancer registries, in the Western world, such as the United States (Davies and Welch, 2006), Canada, and in many European Countries (Leenhardt et al, 2004; Yu et al, 2010) (Table 1). The increase in TC might be attributed to more intensive and sensitive thyroid nodule diagnostic procedures (thyroid ultrasound and fine-needle aspiration biopsies) and the results of improved diagnosis of subclinical cancers (Davies and Welch, 2006; Kent et al, 2007). Pathologists have begun to dissect thinner slices of the gland (less than 2 mm) and frequently sample macroscopically evident lesions and the entire thyroid gland (Pazaitou-Panayiotou et al, 2007; Boucek et al, 2009)
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