title: Serum irisin levels are lower in patients with breast cancer: association with disease diagnosis and tumor characteristics.
abstract: BACKGROUND
  Irisin is a recently discovered myokine, involved in the browning of white adipose tissue. To date, its function has been mainly associated with energy homeostasis and metabolism, and it has been proposed as a promising therapeutic target for obesity and metabolic diseases. This is the first study investigating the role of irisin in human breast cancer.
  
  
  METHODS
  Participants included one hundred and one (101) female patients with invasive ductal breast cancer and fifty one (51) healthy women. Serum levels of irisin, leptin, adiponectin and resistin were quantified in duplicates by ELISA. Serum levels of CEA, CA 15-3 and Her-2/neu were measured on an immunology analyzer. The association between irisin and breast cancer was examined by logistic regression analysis. The feasibility of serum irisin in discriminating breast cancer patients was assessed by ROC curve analysis. Potential correlations with demographic, anthropometric and clinical parameters, with markers of adiposity and with breast tumor characteristics were also investigated.
  
  
  RESULTS
  Serum levels of irisin were significantly lower in breast cancer patients compared to controls (2.47 ± 0.57 and 3.24 ± 0.66 μg/ml, respectively, p < 0.001). A significant independent association between irisin and breast cancer was observed by univariate and multivariate analysis (p < 0.001). It was estimated that a 1 unit increase in irisin levels leads to a reduction in the probability of breast cancer by almost 90%. Irisin could effectively discriminate breast cancer patients at a cut-off point of 3.21 μg/ml, with 62.7% sensitivity and 91.1% specificity. A positive association with tumor stage and marginal associations with tumor size and lymph node metastasis were observed (p < 0.05, p < 0.01, p < 0.01, respectively).
  
  
  CONCLUSIONS
  Our novel findings implicate irisin in breast cancer and suggest its potential application as a new diagnostic indicator of the presence of disease.
authors.affiliation: Research Center, Hellenic Anticancer Institute, Athens, Greece. xprovatopoulou@yahoo.gr.
authors.forename: Xeni
authors.initials: X
authors.lastname: Provatopoulou
authors.affiliation: 1st Department of Propaedeutic Surgery, Hippokratio Hospital, School of Medicine, University of Athens, Athens, Greece. georgiacy@hotmail.com.
authors.forename: Georgia P
authors.initials: GP
authors.lastname: Georgiou
authors.affiliation: Research Center, Hellenic Anticancer Institute, Athens, Greece. kalogerael@yahoo.gr.
authors.forename: Eleni
authors.initials: E
authors.lastname: Kalogera
authors.affiliation: 2nd Department of Surgery, Naval and Veterans Hospital of Athens, Athens, Greece. v_kalles@yahoo.gr.
authors.forename: Vasileios
authors.initials: V
authors.lastname: Kalles
authors.affiliation: 1st Department of Propaedeutic Surgery, Hippokratio Hospital, School of Medicine, University of Athens, Athens, Greece. amatiat@yahoo.com.
authors.forename: Maira A
authors.initials: MA
authors.lastname: Matiatou
authors.affiliation: 1st Department of Propaedeutic Surgery, Hippokratio Hospital, School of Medicine, University of Athens, Athens, Greece. gpapa@hotmail.com.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Papapanagiotou
authors.affiliation: Research Center, Hellenic Anticancer Institute, Athens, Greece. asagkriotis@gmail.com.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Sagkriotis
authors.affiliation: 1st Department of Propaedeutic Surgery, Hippokratio Hospital, School of Medicine, University of Athens, Athens, Greece. zografos@med.uoa.gr.
authors.forename: George C
authors.initials: GC
authors.lastname: Zografos
authors.affiliation: Research Center, Hellenic Anticancer Institute, Athens, Greece. antgouna@otenet.gr.
authors.forename: Antonia
authors.initials: A
authors.lastname: Gounaris
mesh_terms: D052242:Adiponectin / Q000097:blood; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000097:blood* / Q000175:diagnosis; D018270:Carcinoma, Ductal, Breast / Q000097:blood* / Q000175:diagnosis; D016022:Case-Control Studies; D005260:Female; D005353:Fibronectins / Q000097:blood*; D006801:Humans; D020738:Leptin / Q000097:blood; D016015:Logistic Models; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: D052242:Adiponectin; D014408:Biomarkers, Tumor; C577593:FNDC5 protein, human; D005353:Fibronectins; D020738:Leptin