title: Thyroid hormones and selenium status in breast cancer.
abstract: Within a case-control study of postmenopausal breast cancer patients (n = 99) and matched healthy controls (n = 105), thyroid hormone levels were compared and correlated with toenail selenium concentrations. Plasma triiodothyronine (T3) was significantly lower in cases (1.4 +/- 0.4 nmol/l) than in controls (1.6 +/- 0.4 nmol/l), and a strong inverse relationship with breast cancer was observed with an odds ratio of 0.17 (95% CI = 0.08-0.36) in the highest compared with the lowest tertile of T3. Plasma thyroxine and thyroid-stimulating hormone concentrations were similar between cases and controls. Plasma T3 concentration was positively associated with toenail selenium in cases (age-adjusted regression coefficient = 0.049) and controls (age-adjusted regression coefficient = 0.036). Toenail selenium concentrations tended to be lower in cases than in controls, but the differences did not reach statistical significance. Although the disease process per se may explain the lower plasma T3 concentrations, it is also possible, inasmuch as these patients were in early-stage breast cancer, that selenium status may be influencing T3 levels via changes in the activity of the selenoenzyme type 1 iodothyronine deiodinase.
authors.affiliation: Human Nutrition Research Group, University of Ulster, Coleraine, Northern Ireland.
authors.forename: J J
authors.initials: JJ
authors.lastname: Strain
authors.forename: E
authors.initials: E
authors.lastname: Bokje
authors.forename: P
authors.initials: P
authors.lastname: van't Veer
authors.forename: J
authors.initials: J
authors.lastname: Coulter
authors.forename: C
authors.initials: C
authors.lastname: Stewart
authors.forename: H
authors.initials: H
authors.lastname: Logan
authors.forename: W
authors.initials: W
authors.lastname: Odling-Smee
authors.forename: R A
authors.initials: RA
authors.lastname: Spence
authors.forename: K
authors.initials: K
authors.lastname: Steele
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000502:physiology; D008875:Middle Aged; D009262:Nails / Q000737:chemistry; D009660:Northern Ireland / Q000453:epidemiology; D012044:Regression Analysis; D012307:Risk Factors; D012643:Selenium / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014034:Toes; D014284:Triiodothyronine / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D014284:Triiodothyronine; D013972:Thyrotropin; D007453:Iodide Peroxidase; D012643:Selenium; D013974:Thyroxine