title: Progesterone or progestin as menopausal ovarian hormone therapy: recent physiology-based clinical evidence.
abstract: OBJECTIVE
  Provide evidence-based recent data on oral micronized progesterone (OMP) and progestins in menopausal hormonal therapy (MHT).
  
  
  RESULTS
  Medroxyprogesterone acetate (MPA) increases breast cancer acting through the glucocorticoid receptor; progestins in MHT increase thrombosis more than oral estrogens; MPA, but not OMP or other progestins, increase monocyte cell endothelium adhesion; MPA and estradiol (E2)/MPA have negative brain effects, whereas E2/progesterone (P4) has neuroregenerative brain effects. The 'window of opportunity' cardiovascular disease hypothesis is not supported by a randomized controlled trial showing that transdermal estradiol with sequential OMP in early menopause does not prevent increased carotid intimal media thickness; P4 in the cardiac electrical system opposes E2 effects and prevents sudden death/long QT syndrome; transdermal estradiol/OMP does not increase venous thromboembolism in observational data. P4 decreases breast cell proliferation and improves prognosis through P4 receptor alteration of estrogen receptor α genetic effects; OMP with conjugated equine estrogen (CEE)/estrogen (E)/E2 does not increase breast cancer in two prospective cohorts, one population-based. Endometrial cancer is increased in MHT of CEE/E/E2+cyclic OMP at 200 mg/day.
  
  
  CONCLUSIONS
  New data show CEE/E/E2+MPA/P mechanisms for negative breast cancer, venous thromboembolism, cardiovascular system, and brain effects. OMP/P4 counterbalances CEE/E/E2-related negative effects on breast cancer and long QT syndrome. OMP effectively treats vasomotor symptoms and sleep disturbances, and could safely be used alone for symptomatic menopause.
authors.affiliation: Endocrinology and Metabolism, Centre for Menstrual Cycle and Ovulation Research (CeMCOR), Department of Medicine, School of Population and Public Health, University of British Columbia, Vancouver Coastal Health Research Institute, Vancouver, Canada.
authors.forename: Jerilynn C
authors.initials: JC
authors.lastname: Prior
mesh_terms: D001842:Bone and Bones / Q000502:physiology; D001921:Brain / Q000502:physiology; D001940:Breast / Q000502:physiology; D002318:Cardiovascular Diseases / Q000517:prevention & control; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects; D006801:Humans; D008593:Menopause; D011374:Progesterone / Q000009:adverse effects / Q000627:therapeutic use*; D011372:Progestins / Q000009:adverse effects / Q000627:therapeutic use*; D012893:Sleep Wake Disorders / Q000188:drug therapy; D014666:Vasomotor System / Q000187:drug effects; D054556:Venous Thromboembolism / Q000139:chemically induced
chemical_list: D011372:Progestins; D011374:Progesterone