title: Association of leukocyte mitochondrial DNA copy number with colorectal cancer risk: Results from the Shanghai Women's Health Study.
abstract: BACKGROUND
  Mitochondria play an important role in cellular energy metabolism, free radical production, and apoptosis, and thus may be involved in cancer development.
  
  
  METHODS
  We evaluated mitochondrial DNA (mtDNA) copy number in peripheral leukocytes in relation to colorectal cancer risk in a case-control study of 444 colorectal cancer cases and 1,423 controls nested in the Shanghai Women's Health Study, a population-based, prospective cohort study. Relative mtDNA copy number was determined by a quantitative real-time PCR assay using peripheral leukocyte DNA samples collected at the time of study enrollment, before cancer diagnosis.
  
  
  RESULTS
  We found that baseline mtDNA copy number was lower among women who subsequently developed colorectal cancer [geometric mean, 0.277; 95% confidence interval (CI), 0.269-0.285] than among women who remained cancer-free (geometric mean, 0.288; 95% CI, 0.284-0.293; P = 0.0153). Multivariate adjusted ORs were 1.26 (95% CI, 0.93-1.70) and 1.44 (95% CI, 1.06-1.94) for the middle and lower tertiles of mtDNA copy number, respectively, compared with the upper tertile (highest mtDNA copy number; Ptrend = 0.0204). The association varied little by the interval between blood collection and cancer diagnosis.
  
  
  CONCLUSIONS
  Our data suggest that mtDNA copy number measured in peripheral leukocytes may be a potential biomarker useful for colorectal cancer risk assessment.
  
  
  CONCLUSIONS
  If confirmed, mtDNA copy number measured in peripheral leukocytes may be a biomarker useful for colorectal cancer risk assessment.
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee. School of Public Health, Guilin Medical University, Guilin, Guangxi, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Huang
authors.affiliation: Department of Epidemiology, Shanghai Cancer Institute, Shanghai, China.
authors.forename: Yu-Tang
authors.initials: YT
authors.lastname: Gao
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee.
authors.forename: Xiao-Ou
authors.initials: XO
authors.lastname: Shu
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee.
authors.forename: Wanqing
authors.initials: W
authors.lastname: Wen
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee.
authors.forename: Gong
authors.initials: G
authors.lastname: Yang
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Li
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee.
authors.forename: Regina
authors.initials: R
authors.lastname: Courtney
authors.affiliation: Division of Cancer Epidemiology and Genetics, Department of Health and Human Services, National Cancer Institute, NIH, Bethesda, Maryland.
authors.forename: Bu-Tian
authors.initials: BT
authors.lastname: Ji
authors.affiliation: Department of Epidemiology, Shanghai Cancer Institute, Shanghai, China.
authors.forename: Hong-Lan
authors.initials: HL
authors.lastname: Li
authors.affiliation: Division of Cancer Epidemiology and Genetics, Department of Health and Human Services, National Cancer Institute, NIH, Bethesda, Maryland.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Purdue
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee.
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.affiliation: Division of Epidemiology and Vanderbilt Epidemiology Center, Department of Medicine, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee. qiuyin.cai@vanderbilt.edu.
authors.forename: Qiuyin
authors.initials: Q
authors.lastname: Cai
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics*; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D003110:Colonic Neoplasms / Q000453:epidemiology / Q000235:genetics*; D056915:DNA Copy Number Variations; D004272:DNA, Mitochondrial; D005260:Female; D006801:Humans; D007962:Leukocytes; D008875:Middle Aged; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000453:epidemiology / Q000235:genetics*; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; D004272:DNA, Mitochondrial