title: Urinary rubidium in breast cancers.
abstract: BACKGROUND
  Rubidium is a putative anticancer agent, but no studies have been performed on the association of rubidium levels in biospecimen with breast cancer risk and the potential as a biomarker of the risk assessment.
  
  
  METHODS
  Survey data and urine specimens were collected from 240 women with incident invasive breast cancer before their treatments and 246 age-matched female controls between October 2009 and July 2010. Urinary concentrations of rubidium were determined by inductively coupled plasma mass spectrometry.
  
  
  RESULTS
  Creatinine-adjusted levels [median (25th, 75th) ug/g] of rubidium in cases [2253.01(1606.81, 3110.46)] were significantly lower than that in the controls [2921.85 (2367.94, 4142.04)]. After adjustment for potential risk factors of breast cancer, women in the second and highest tertile decreased risk of breast cancer in a dose-dependent manner as compared with those in the lowest tertile [ORs and 95% CIs were 0.45 (0.27-0.73) and 0.22 (0.13-0.38), respectively]. The area under the receive-operating-characteristic curve for urinary rubidium level was 0.697 (95% CI: 0.650-0.743).
  
  
  CONCLUSIONS
  The urinary levels of rubidium were significantly and inversely associated with risk of breast cancer and had potential to be a biomarker for breast cancer risk assessment.
authors.affiliation: The School of Public Health, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Su
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Chen
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: He
authors.forename: Xue-Jiao
authors.initials: XJ
authors.lastname: Yuan
authors.forename: Yu-Ling
authors.initials: YL
authors.lastname: Cen
authors.forename: Feng-Xi
authors.initials: FX
authors.lastname: Su
authors.forename: Lu-Ying
authors.initials: LY
authors.lastname: Tang
authors.forename: Ai-Hua
authors.initials: AH
authors.lastname: Zhang
authors.forename: Wei-Qing
authors.initials: WQ
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Lin
authors.forename: Shen-Ming
authors.initials: SM
authors.lastname: Wang
authors.forename: Ze-Fang
authors.initials: ZF
authors.lastname: Ren
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000652:urine*; D016022:Case-Control Studies; D003404:Creatinine / Q000097:blood; D005260:Female; D006801:Humans; D008875:Middle Aged; D012413:Rubidium / Q000652:urine*
chemical_list: D003404:Creatinine; D012413:Rubidium