title: Elevated Serum Levels of Retinol-Binding Protein 4 Are Associated with Breast Cancer Risk: A Case-Control Study.
abstract: BACKGROUND
  Retinol binding protein 4 (RBP4) is a recently identified adipokine that is elevated in patients with obesity or type 2 diabetes. A growing body of research has shown that RBP4 is associated with several types of cancer. However, no studies have investigated the relationship between serum RBP4 levels and breast cancer risk. We performed a case-control study to evaluate the association between serum RBP4 levels and the risk of breast cancer.
  
  
  METHODS
  From August 2012 to December 2013, four-hundred subjects including 200 patients diagnosed with primary breast cancer and 200 matched healthy women were consecutively enrolled from Affiliated Hospital of Qingdao University Medical College. Blood samples were collected from healthy controls and breast cancer patients before commencement of treatment. Enzyme-linked immunosorbent assay was used to evaluate the serum RBP4 levels in separated serum samples. Meanwhile, the characteristics of breast cancer cases and controls were collected from medical records and pathological data.
  
  
  RESULTS
  The serum levels of RBP4 were significantly higher in patients with breast cancer than that in the healthy control group (33.77±9.92 vs. 28.77±6.47μg/ml, P < 0.05). Compared to the subjects in the lowest quartile of serum RBP4 level, the adjusted ORs (95% CIs) is 2.16(1.01-4.61) and 2.07 (1.07-4.00) for women in the second and highest RBP4 tertile, respectively. For breast cancer patients, patients with PR or ER negative displayed significantly higher serum RBP4 levels than those with PR or ER positive.
  
  
  CONCLUSIONS
  Our results for the first time suggested serum RBP4 levels could be associated with the risk of breast cancer. However, further prospective studies are essential to confirm these observed results.
authors.affiliation: Department of Public Health, Medical College of Qingdao University, Qingdao, Shandong Province, China.
authors.forename: Congcong
authors.initials: C
authors.lastname: Jiao
authors.affiliation: Department of Public Health, Medical College of Qingdao University, Qingdao, Shandong Province, China.
authors.forename: Lianhua
authors.initials: L
authors.lastname: Cui
authors.affiliation: Department of Public Health, Medical College of Qingdao University, Qingdao, Shandong Province, China.
authors.forename: Aiguo
authors.initials: A
authors.lastname: Ma
authors.affiliation: Department of Public Health, Medical College of Qingdao University, Qingdao, Shandong Province, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: Department of Public Health, Medical College of Qingdao University, Qingdao, Shandong Province, China.
authors.forename: Hongzong
authors.initials: H
authors.lastname: Si
mesh_terms: D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D016017:Odds Ratio; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D054839:Retinol-Binding Proteins, Plasma / Q000032:analysis*; D012307:Risk Factors
chemical_list: D015415:Biomarkers; C101326:RBP4 protein, human; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D054839:Retinol-Binding Proteins, Plasma