title: Association between 8-oxo-7,8-dihydro-2'-deoxyguanosine excretion and risk of postmenopausal breast cancer: nested case-control study.
abstract: BACKGROUND
  Oxidative stress may be important in carcinogenesis and a possible risk factor for breast cancer. The urinary excretion of oxidatively generated biomolecules, such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), represents biomarkers of oxidative stress, reflecting the rate of global damage to DNA in steady state.
  
  
  METHODS
  In a nested case-control design, we examined associations between urinary excretion of 8-oxodG and risk of breast cancer in a population-based cohort of 24,697 postmenopausal women aged 50 to 64 years with 3 to 7 years follow-up. The accruing cases of breast cancer were matched to controls by age at diagnosis, baseline age, and hormone replacement therapy (HRT). Spot urine samples collected at entry was analyzed for 8-oxodG by high-performance liquid chromatography with electrochemical detection. Incidence rate ratio (IRR; 95% confidence intervals) based on 336 matched pairs with all information was estimated per unit increase in 8-oxodG divided by creatinine for all and estrogen receptor (ER) positive and negative breast cancers.
  
  
  RESULTS
  There was a borderline significant positive association between 8-oxodG and risk of all breast cancer (IRR: 1.08; 1.00-1.17 per unit increase in nmol/mmol creatinine). This association was significant with respect to the risk of ER-positive cancer (IRR: 1.11; 1.01-1.23) and among women not using HRT (IRR: 1.11; 0.97-1.26) or with low dietary iron intake (IRR: 1.10; 1.06-1.37 per unit increase) for all breast cancer.
  
  
  CONCLUSIONS
  We observed positive association between 8-oxodG excretion and risk of especially ER-positive breast cancer.
  
  
  CONCLUSIONS
  Our results suggest that oxidative stress with damage to DNA is important for the development of breast cancer.
authors: Department of Public Health, Section of Enviromental Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. stl@sund.ku.dk
authors: Steffen
authors: S
authors: Loft
authors: Anja
authors: A
authors: Olsen
authors: Peter
authors: P
authors: Møller
authors: Henrik E
authors: HE
authors: Poulsen
authors: Anne
authors: A
authors: Tjønneland
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D014408:Biomarkers, Tumor / Q000652:urine*; D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics / Q000378:metabolism / Q000652:urine*; D016022:Case-Control Studies; D015331:Cohort Studies; D004249:DNA Damage; D003718:Denmark / Q000453:epidemiology; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000652:urine; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D017698:Postmenopause / Q000235:genetics / Q000652:urine*; D011446:Prospective Studies; D011960:Receptors, Estrogen / Q000096:biosynthesis; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; D011960:Receptors, Estrogen; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine