Journal of the National Cancer Institute Advance Access originally published online on November 5, 2009
JNCI Journal of the National Cancer Institute 2009 101(22):1575-1583; doi:10.1093/jnci/djp354
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© The Author 2009. Published by Oxford University Press. All rights reserved.
ARTICLES |
Papillary Thyroid Cancer Incidence in the Volcanic Area of Sicily
Affiliations of authors: Endocrinology Division, Department of Internal and Specialistic Medicine, University of Catania Medical School, Garibaldi-Nesima Hospital, Catania, Italy (GP, CS, SA, FF, PM, RV); INSERM U605, Villejuif, France (FDV); Endocrinology Division, Cervello Hospital, Palermo, Italy (GDA, MA); Endocrinology, University of Palermo Medical School, Palermo, Italy (CG); Sicilian Regional Epidemiology Observatory, Palermo, Italy (GD); Endocrinology, University of Messina Medical School, Messina, Italy (FV, FT); Environment Protection Regional Agency, Sicily, Italy (DMP)
Correspondence to: Gabriella Pellegriti, MD, PhD, Endocrinology Division, University of Catania Medical School, Garibaldi-Nesima Hospital, Via Palermo 636, 95122 Catania, Italy (e-mail: gabriellapellegriti{at}hotmail.com).
Background: The steadily increasing incidence of thyroid cancer has been attributed mostly to more sensitive thyroid nodule screening. However, various environmental factors, such as those associated with volcanic areas, cannot be excluded as risk factors. We evaluated thyroid cancer incidence in Sicily, which has a homogenous population and a province (Catania) that includes the Mt Etna volcanic area.
Methods: In a register-based epidemiological survey, we collected all incident thyroid cancers in Sicily from January 1, 2002, through December 31, 2004. The age-standardized incidence rate for the world population (ASRw) was calculated and expressed as the number of thyroid cancer diagnoses per 100 000 residents per year. The association of thyroid cancer incidence rate with sex, age, tumor histotype, and various environmental factors was evaluated by modeling the variation of the ASRw. All statistical tests were two-sided.
Results: In 2002–2004, 1950 incident thyroid cancers were identified in Sicily (among women, ASRw = 17.8, 95% confidence interval [CI] = 16.9 to 18.7; and among men, ASRw = 3.7, 95% CI = 3.3 to 4.1). Although the percentage of thyroid cancers that were microcarcinomas (ie, 
10 mm) and ratio of men to women with thyroid cancer were similar in all nine Sicilian provinces, thyroid cancer incidence was statistically significantly higher in the province of Catania (among women, ASRw = 31.7, 95% CI = 29.1 to 34.3; and among men, ASRw = 6.4, 95% CI = 5.2 to 7.5) than in the rest of Sicily (among women, ASRw = 14.1, 95% CI = 13.2 to 15.0; and among men, ASRw = 3.0, 95% CI = 2.6 to 3.4) (all P values < .001). Incidence of papillary, but not follicular or medullary, cancers was statistically significantly increased in Catania province, and papillary tumors from patients in Catania more frequently carried the BRAF V600E gene mutation (55 [52%] of 106 tumors) than tumors from patients elsewhere in Sicily (68 [33%] of 205 tumors) (relative risk = 1.7, 95% CI = 1.0 to 2.8, P = .02). Cancer incidence was statistically significantly lower in rural areas than in urban areas of Sicily (P = .003). No association with mild iodine deficiency or industrial installations was found. Levels of many elements (including boron, iron, manganese, and vanadium) in the drinking water of Catania province often exceeded maximum admissible concentrations, in contrast to water in the rest of Sicily.
Conclusion: Residents of Catania province with its volcanic region appear to have a higher incidence of papillary thyroid cancer than elsewhere in Sicily.
| CONTEXT AND CAVEATS Prior knowledge Although increased incidence of thyroid cancer worldwide has been attributed to more sensitive screening, environmental factors, including those associated with volcanic areas, have not been excluded as risk factors. Study design Data on all incident thyroid cancers in Sicily were collected from 2002 through 2004. The association of thyroid cancer incidence rate with sex, age, tumor histotype, and various environmental factors was evaluated. Contribution Thyroid cancer incidence was statistically significantly higher in the province of Catania, which contains the Mt Etna volcanic area, than in the rest of Sicily. Incidence of papillary, but not follicular or medullary, cancers was statistically significantly increased in Catania province, and papillary tumors from patients in Catania more frequently carried the BRAF V600E gene mutation that has been associated with thyroid cancer. Implications Residents of the volcanic environment of Mt Etna appear to be at increased risk of papillary thyroid cancer. Investigations to identify specific risk factors for thyroid cancer in this and other volcanic environments are warranted. Limitations The population of Sicily is fairly homogenous and so results may not be generalizable to other populations. It was assumed, without evidence, that the composition and concentrations of volcanic contaminants were similar over time. No dose–response associations were identified. Individual-level exposure data to volcanic contaminants were not available. From the Editors
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Manuscript received March 3, 2009; revised August 31, 2009; accepted September 10, 2009.
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