Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect.
BACKGROUND
Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall.


METHODS
A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome.


RESULTS
Overall, 399 (0.5%) participants were diagnosed with breast cancer and 2,629 (3.0%) had false positive recall. Compared to never users of HRT, the adjusted relative risk (95% CI) of false positive recall was: 1.62 (1.43-1.83), 1.80 (1.62-2.01) and 0.76 (0.52-1.10) in current users of oestrogen-only HRT, oestrogen-progestagen HRT and tibolone, respectively (p (heterogeneity) < 0.0001); 1.65 (1.43-1.91), 1.49 (1.22-1.81) and 2.11 (1.45-3.07) for current HRT used orally, transdermally or via an implant, respectively (p (heterogeneity) = 0.2); and 1.84 (1.67-2.04) and 1.75 (1.49-2.06) for sequential and continuous oestrogen-progestagen HRT, respectively (p (heterogeneity) = 0.6). The relative risk of false positive recall among current users appeared to increase with increasing time since menopause, but did not vary significantly according to any other factors examined, including duration of use, hormonal constituents, dose, whether single- or two-view screening was used, or the woman's personal characteristics.


CONCLUSIONS
Current use of oestrogen-only and oestrogen-progestagen HRT, but not tibolone, increases the risk of false positive recall at screening.
Banks
Emily
E
National Centre for Epidemiology and Population Health, Australian National University, ACT 0200, Australia. emily.banks@anu.edu.au
Reeves
Gillian
G
Beral
Valerie
V
Bull
Diana
D
Crossley
Barbara
B
Simmonds
Moya
M
Hilton
Elizabeth
E
Bailey
Stephen
S
Barrett
Nigel
N
Briers
Peter
P
English
Ruth
R
Jackson
Alan
A
Kutt
Elizabeth
E
Lavelle
Janet
J
Rockall
Linda
L
Wallis
Matthew G
MG
Wilson
Mary
M
Patnick
Julietta
J
D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D020847:Estrogen Receptor Modulators / Q000627:therapeutic use; D015914:Estrogen Replacement Therapy; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008327:Mammography / Q000592:standards*; D008403:Mass Screening; D008875:Middle Aged; D009652:Norpregnenes / Q000627:therapeutic use; D017698:Postmenopause; D011372:Progestins / Q000627:therapeutic use; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity
D020847:Estrogen Receptor Modulators; D009652:Norpregnenes; D011372:Progestins; C027385:tibolone