title: Thyroid cancer incidence by histological type and related variants in a mildly iodine-deficient area of Northern Italy, 1998 to 2009.
abstract: BACKGROUND
  The incidence of thyroid cancer is increasing in several countries. However, the issue of whether this applies to all different histological types and related variants is poorly addressed.
  
  
  METHODS
  All incident thyroid cancers diagnosed between 1998 and 2009 in a mildly iodine-deficient area in northern Italy were derived from a population-based tumor registry. Stage of disease, size of the tumor, focality, and histological variants were recorded from a review of pathology reports and slides. The mean annual increase (MAI) of the standardized incidence rate was calculated over the entire 12-year period of observation and a standardized rate ratio was evaluated to compare the mean standardized incidence between 2 periods of 6 years each (1998-2003 vs 2004-2009).
  
  
  RESULTS
  In total, 980 cases were considered. An increase in the incidence trend for all thyroid tumors was demonstrated; the increase was found to be continuous from 1998 to 2002 but not afterward. The cancer incidence increased in both male and female subjects. Papillary thyroid carcinoma (PTC), the follicular variant of PTC, the tall cell variant of PTC (TCV-PTC), and Hurthle cell carcinoma (HC) showed the most relevant changes in incidence whereas follicular carcinoma was not found to be significantly affected. TCV-PTC was the only histological type to demonstrated a significant (P < .01) proportional increase in the second 6-year period of observation. Only TCV-PTC and HC were found to display a significant MAI after 2002.
  
  
  CONCLUSIONS
  The incidence of thyroid cancer has increased within the last decade, an increase that is accounted for mostly by differentiated tumors. The most significant increases were documented for aggressive variants of basic histotypes.
authors.affiliation: Department of Internal Medicine and Biomedical Sciences, Section of Geriatrics, Endocrine Unit, University of Parma, Parma, Italy. ceresini@unipr.it
authors.forename: Graziano
authors.initials: G
authors.lastname: Ceresini
authors.forename: Luigi
authors.initials: L
authors.lastname: Corcione
authors.forename: Maria
authors.initials: M
authors.lastname: Michiara
authors.forename: Paolo
authors.initials: P
authors.lastname: Sgargi
authors.forename: Giulio
authors.initials: G
authors.lastname: Teresi
authors.forename: Annalisa
authors.initials: A
authors.lastname: Gilli
authors.forename: Elisa
authors.initials: E
authors.lastname: Usberti
authors.forename: Enrico
authors.initials: E
authors.lastname: Silini
authors.forename: Gian Paolo
authors.initials: GP
authors.lastname: Ceda
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D002277:Carcinoma / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D015994:Incidence; D007455:Iodine / Q000172:deficiency*; D007558:Italy / Q000453:epidemiology; D008297:Male; D011379:Prognosis; D012042:Registries; D015996:Survival Rate; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology
chemical_list: D007455:Iodine