title: Modified effect of urinary cadmium on breast cancer risk by selenium.
abstract: BACKGROUND
  Previous experimental studies have shown an antagonistic interaction between cadmium and selenium. We explored the interaction between cadmium and selenium on human breast cancer risk.
  
  
  METHODS
  A case-control study, enrolled 240 incident invasive breast cancer patients and 246 age-matched controls from 2 hospitals, was conducted in Guangzhou, China. Inductively coupled plasma mass spectrometry was used to examine urinary concentrations of cadmium and selenium. Association and interaction of the metal levels with breast cancer risk were tested using generalized additive and logistic regression models.
  
  
  RESULTS
  As continuous variables, urinary cadmium [OR (95% CI): 1.16 (1.01-1.34)] but not selenium was significantly linearly associated with breast cancer risk. As tertiles, urinary cadmium did not significantly increase breast cancer risk; whereas women with the second tertile of selenium concentration had a significantly decreased risk of breast cancer as compared with those in the lowest tertile [OR (95% CI): 0.50 (0.30-0.81)]. Among the women with the lowest tertile of selenium, the highest tertile of cadmium significantly increased the risk of breast cancer [OR (95% CI): 2.83 (1.18-6.86)] compared to the lowest tertile of cadmium. A multiplicative interaction was found between tertiles of cadmium and selenium on breast cancer risk (P=0.018), particularly among postmenopausal women.
  
  
  CONCLUSIONS
  These results suggested that the association of urinary cadmium with breast cancer risk was modified by urinary selenium.
authors.affiliation: The School of Public Health, Sun Yat-sen University, Guangzhou, China.
authors.forename: Xue-Ling
authors.initials: XL
authors.lastname: Wei
authors.affiliation: The School of Public Health, Sun Yat-sen University, Guangzhou, China; The Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: He
authors.affiliation: The School of Public Health, Sun Yat-sen University, Guangzhou, China.
authors.forename: Yu-Ling
authors.initials: YL
authors.lastname: Cen
authors.affiliation: The School of Public Health, Sun Yat-sen University, Guangzhou, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Su
authors.affiliation: The School of Public Health, Sun Yat-sen University, Guangzhou, China.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Chen
authors.affiliation: The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Lin
authors.affiliation: The Guangdong Prevention and Treatment Center for Occupational Diseases, Guangzhou, China.
authors.forename: Bang-Hua
authors.initials: BH
authors.lastname: Wu
authors.affiliation: The Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Feng-Xi
authors.initials: FX
authors.lastname: Su
authors.affiliation: The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China. Electronic address: tangly@mail.sysu.edu.cn.
authors.forename: Lu-Ying
authors.initials: LY
authors.lastname: Tang
authors.affiliation: The School of Public Health, Sun Yat-sen University, Guangzhou, China. Electronic address: renzef@mail.sysu.edu.cn.
authors.forename: Ze-Fang
authors.initials: ZF
authors.lastname: Ren
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000139:chemically induced* / Q000652:urine; D002104:Cadmium / Q000009:adverse effects* / Q000652:urine; D005260:Female; D006801:Humans; D008875:Middle Aged; D012643:Selenium / Q000494:pharmacology*
chemical_list: D002104:Cadmium; D012643:Selenium
keywords: Breast cancer; Cadmium; Risk; Selenium; Urine