title: Dietary iodine and thyroid cancer risk in French Polynesia: a case-control study.
abstract: BACKGROUND
  French Polynesia has one of the world's highest thyroid cancer incidence rates. Iodine is suspected to play a role in this high incidence. The objective of this study was to assess whether low dietary iodine is related to a higher risk of thyroid cancer in the French Polynesian population.
  
  
  METHODS
  A case-control study was performed among native residents of French Polynesia. It included 229 cases of differentiated thyroid cancer diagnosed between 1979 and 2004 (203 women, 26 men) matched with 371 population controls (324 women, 47 men) on the date of birth. The current study is focused on dietary iodine intake and fish consumption (food rich in iodine) and analyzed by conditional logistic regression.
  
  
  RESULTS
  Daily dietary iodine intake was insufficient (<150 μg/day) in 60% of both cases and controls. A decreased risk of thyroid cancer was observed with a higher consumption of fish (p(trend)=0.008) and shellfish (p(trend)=0.002), and also with a higher dietary iodine intake (p(trend)=0.03). There was no significant interaction between the effects of the thyroid radiation dose and the dietary iodine intake (p=0.2).
  
  
  CONCLUSIONS
  French Polynesia is a mild iodine deficiency area in which a higher consumption of food from the sea and a higher dietary iodine intake are significantly associated with a decreased risk of thyroid cancer. The quantification of this reduction requires specific investigation of iodine intake in traditional Polynesian food.
authors.affiliation: Radiation Epidemiology Group, CESP Center for Research in Epidemiology and Population Health, U1018 INSERM, Villejuif, France.
authors.forename: Énora
authors.initials: É
authors.lastname: Cléro
authors.forename: Françoise
authors.initials: F
authors.lastname: Doyon
authors.forename: Vaïana
authors.initials: V
authors.lastname: Chungue
authors.forename: Frédérique
authors.initials: F
authors.lastname: Rachédi
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Boissin
authors.forename: Joseph
authors.initials: J
authors.lastname: Sebbag
authors.forename: Larrys
authors.initials: L
authors.lastname: Shan
authors.forename: Frédérique
authors.initials: F
authors.lastname: Bost-Bezeaud
authors.forename: Patrice
authors.initials: P
authors.lastname: Petitdidier
authors.forename: Eric
authors.initials: E
authors.lastname: Dewailly
authors.forename: Carole
authors.initials: C
authors.lastname: Rubino
authors.forename: Florent
authors.initials: F
authors.lastname: de Vathaire
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002291:Carcinoma, Papillary / Q000453:epidemiology; D018265:Carcinoma, Papillary, Follicular / Q000453:epidemiology; D016022:Case-Control Studies; D002648:Child; D003625:Data Collection; D004032:Diet; D004034:Diet Surveys; D002149:Energy Intake; D005260:Female; D005399:Fishes; D006801:Humans; D007455:Iodine / Q000172:deficiency / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D011114:Polynesia / Q000453:epidemiology; D012306:Risk; D017747:Seafood; D012737:Sex Factors; D012758:Shellfish; D011795:Surveys and Questionnaires; D013964:Thyroid Neoplasms / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D007455:Iodine