title: Assay of serum E2 concentration in postmenopausal breast cancer patients using a high-sensitivity RIA method is generally useful.
abstract: BACKGROUND
  Serum E2 must be monitored for aromatase inhibitor (AI) therapy, but conventional assays lack sensitivity.
  
  
  METHODS
  Forty amenorrheic breast cancer patients scheduled for AI treatment but requiring hormonological confirmation of their menopausal status were studied. Serum E2 data generated by high-sensitivity RIA and by LC-MS/MS were analyzed for correlation.
  
  
  RESULTS
  RIA gave a higher E2 value than LC-MS/MS in 62% of cases, but there was a significant positive correlation. Patients whose E2 levels by RIA were ≥ 2.5 pg/mL higher than those by LC-MS/MS (RIA-H group) and all other patients (RIA-N group) were compared. Both groups showed strong correlations between the two assay methods. With both methods patients with a high BMI had significantly elevated E2. Multiple regression analysis used age, age at menarche, number of births and BMI as explanatory variables. Significant variables were the BMI with LC-MS/MS, and both BMI and age with RIA. The RIA-H and RIA-N groups showed no difference in regard to the BMI, whereas the age was significantly lower in the RIA-H group.
  
  
  CONCLUSIONS
  Serum E2 levels determined for postmenopausal women by RIA and LC-MS/MS generally correlated well. High-sensitivity RIA is a potentially useful clinical assay, but it overestimated serum E2 in some women. J. Med. Invest. 63: 236-240, August, 2016.
authors.affiliation: Department of Oncological and Regenerative Surgery, Institute of Health Biosciences, the University of Tokushima.
authors.forename: Masami
authors.initials: M
authors.lastname: Morimoto
authors.forename: Masako
authors.initials: M
authors.lastname: Takahashi
authors.forename: Junko
authors.initials: J
authors.lastname: Honda
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yoshida
authors.forename: Mitsuteru
authors.initials: M
authors.lastname: Yoshida
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Toba
authors.forename: Issei
authors.initials: I
authors.lastname: Imoto
authors.forename: Akira
authors.initials: A
authors.lastname: Tangoku
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Sasa
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000097:blood*; D002853:Chromatography, Liquid; D004958:Estradiol / Q000097:blood*; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D011863:Radioimmunoassay / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D004958:Estradiol