title: Type of hormone therapy and risk of misclassification at mammography screening.
abstract: OBJECTIVE
  Current users of hormone therapy (HT) are known to have a lower accuracy of mammography screening than do never users. We studied whether the risk of misclassification depends on type of hormone, administration, regimen, and dose of the therapy.
  
  
  METHODS
  We linked data from mammography screening registers with drug prescription registers from Fyn, Denmark to identify current and never HT users among screening participants. We compared false-positive risks and interval cancer proportions between current users of different HT preparations, taking women's age, breast density, screen number, and age of comparison mammogram into account.
  
  
  RESULTS
  Estrogen therapy users had a significantly higher false-positive risk when the administration was by injection instead of oral (relative risk [RR], 2.37; 95% CI, 1.37-4.09). Women using sequential estrogen plus progestogen therapy had a significantly higher false-positive risk (RR, 1.94; 95% CI, 1.16-3.26) and a nonsignificantly higher interval cancer proportion (RR, 4.29; 95% CI, 0.69-26.53) when the administration of both hormones was transdermal instead of oral. Using tibolone instead of comparable hormones gave a nonsignificantly lower false-positive risk and a nonsignificantly higher interval cancer proportion.
  
  
  CONCLUSIONS
  Our data showed increased risks of misclassification at mammography screening among women using estrogen injections or transdermal, sequential estrogen plus progestogen. Tibolone seems to offer no advantage regarding accuracy of screening mammography.
authors: Institute of Public Health, University of Copenhagen, Copenhagen N, Denmark. S.Njor@pubhealth.ku.dk
authors: Sisse H
authors: SH
authors: Njor
authors: Jesper
authors: J
authors: Hallas
authors: Walter
authors: W
authors: Schwartz
authors: Elsebeth
authors: E
authors: Lynge
authors: Anette Tønnes
authors: AT
authors: Pedersen
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D002277:Carcinoma / Q000000981:diagnostic imaging*; D003718:Denmark / Q000453:epidemiology; D003951:Diagnostic Errors; D055088:Early Detection of Cancer; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects*; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data*; D008403:Mass Screening; D008875:Middle Aged; D012306:Risk; D016896:Treatment Outcome