title: Comparison of metabolic ratios of urinary estrogens between benign and malignant thyroid tumors in postmenopausal women.
abstract: BACKGROUND
  Estrogen metabolism may be associated with the pathophysiological development of papillary thyroid carcinoma (PTC).
  
  
  METHODS
  To evaluate the differential estrogen metabolism between benign and malignant PTCs, estrogen profiling by gas chromatography-mass spectrometry was applied to urine samples from postmenopausal patients with 9 benign tumors and 18 malignant stage I and III/IV PTCs.
  
  
  RESULTS
  The urinary concentration of 2-methoxyestradiol was significantly lower in the stage I malignant patients (3.5-fold; P < 0.025) than in the benign group. The metabolic ratios of 16α-OH-estrone/estrone and estriol/estradiol, which are responsible for 16α-hydroxylase activity, were increased more than 2.5-fold in the advanced-stage malignant PTC (P < 0.02 each). The more than 6.2-fold decrease in the urinary 2-/16α-hydroxylase ratio in stage III/IV malignant PTC was consistent with the ratio in postmenopausal patients with endocrine gland cancers. In addition, reductive 17β-hydroxysteroid dehydrogenase (17β-HSD; estradiol/estrone or estriol/16α-OH-estrone) was present at significantly higher levels in subjects with stage III/IV malignant PTCs than in benign subjects (>3.5-fold difference; P < 0.002). In particular, the estriol/16α-OH-estrone ratio differentiated between the benign and early-stage malignant patients (P < 0.01).
  
  
  CONCLUSIONS
  Increased 16α-hydroxylation and/or a decreased 2-/16α-ratio, as well increased reductive 17β-HSD, with regard to estrogen metabolism could provide potential biomarkers. The devised profiles could be useful for differentiating malignant thyroid carcinomas from benign adenomas in postmenopausal women.
authors.forename: Ju-Yeon
authors.initials: JY
authors.lastname: Moon
authors.forename: Eun Jig
authors.initials: EJ
authors.lastname: Lee
authors.forename: Woong Youn
authors.initials: WY
authors.lastname: Chung
authors.forename: Myeong Hee
authors.initials: MH
authors.lastname: Moon
authors.forename: Bong Chul
authors.initials: BC
authors.lastname: Chung
authors.affiliation: Future Convergence Research Division, Korea Institute of Science and Technology, 39-1 Hawolkok-dong, Seoul 136-791, Korea. mh_choi@kist.re.kr.
authors.forename: Man Ho
authors.initials: MH
authors.lastname: Choi