title: Liquid chromatography tandem mass spectrometry determination of free and conjugated estrogens in breast cancer patients before and after exemestane treatment.
abstract: We report liquid chromatographic separation with tandem mass spectrometry determination of 12 endogenous estrogens and their intact conjugates in blood and urine and its application to study effects of exemestane treatment on estrogen generation and metabolism in postmenopausal women with estrogen-dependent breast cancer. A 0.5 mL aliquot of each urine or serum sample is fractionated with solid phase extraction to a fraction of free estrogen and another fraction of their conjugates. The reversed phase LC/MS/MS determines dansylated estrogens with positive ionization and intact conjugates with negative ionization. The method provides reproducible separation and limit of detection as low as 1 pg mL(-1) for free estrogens and 0.03 ng mg(-1) creatinine for the conjugates in serum and urine samples. The method enabled us to acquire unique concentration profiles of 12 endogenous estrogens and their intact conjugates in 30 breast cancer patients before and after one month of exemestane treatment. Exemestane suppressed total serum and urinary estrogens by 11-97% (P<0.0001) and 8.7-91% (P<0.0001), respectively. Specifically, these data show that exemestane preferentially suppressed E1, E1-3S, E1-3G, and E2-17G more than other estrogens. Linear regression analysis of estrogen concentrations before and after treatment showed correlation coefficients of 0.8385 (n=289, P<0.0001) and 0.8863 (n=360, P<0.0001). This study provides urinary and blood estrogen concentration profiles in breast cancer patients to demonstrate the effect of exemestane on estrogen generation, supporting inhibition of aromatase activity.
authors: Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada T6G 2G3.
authors: Yuli
authors: Y
authors: Zhao
authors: Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada T6G 2G3.
authors: Jessica M
authors: JM
authors: Boyd
authors: Division of Medical Oncology, Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Cross Cancer Institute, Edmonton, AB, Canada T6G 1Z2.
authors: Michael B
authors: MB
authors: Sawyer
authors: Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada T6G 2G3. Electronic address: xingfang.li@ualberta.ca.
authors: Xing-Fang
authors: XF
authors: Li
mesh_terms: D000730:Androstadienes / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy*; D002851:Chromatography, High Pressure Liquid; D045166:Estradiol Congeners / Q000032:analysis* / Q000097:blood / Q000652:urine; D004967:Estrogens / Q000032:analysis* / Q000097:blood / Q000652:urine; D005260:Female; D006801:Humans; D017698:Postmenopause; D052616:Solid Phase Extraction; D053719:Tandem Mass Spectrometry
chemical_list: D000730:Androstadienes; D000970:Antineoplastic Agents; D045166:Estradiol Congeners; D004967:Estrogens; C056516:exemestane
keywords: Breast cancer; Estrogen conjugates; Estrogens; LC-MS/MS; Serum; Urine