British
Journal of Cancer
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A
population-based cohort study of HRT use and breast cancer in southern Sweden
H.
Olsson, A. Bladström, C. Ingvar, T. R. Möller p 674-677, Volume 85,
Number 5, September
2001 Abstract The overall tumour incidence and breast cancer
incidence related to hormone replacement therapy (HRT) were followed in a
population-based cohort of 29 508 women, aged 25-65 when interviewed in
1990-92. By the end of the follow up in December 1999, there were 226 611
person-years of observation. A total of 1145 malignant tumours were recorded
(expected 1166.6; SIR = 0.98, 95% CI 0.93-1.04). There was a small excess of
breast cancer with 434 observed and 387.69 expected (SIR = 1.12, 95% CI
1.02-1.23). Among about 3 663 ever users of HRT, there was no increase in
overall tumour incidence (SIR = 0.98, 95% CI 0.86-1.12) but a significant
excess of breast cancer (SIR = 1.35, 95% CI 1.09-1.64) compared with never
users (SIR = 1.07, 95% CI 0.96-1.19). Breast cancer increased with increasing
duration of use and for 48-120 months use the SIR was 1.92 (95% CI
1.32-2.70). There was no significant interaction with family history of
breast cancer although an independent additive effect was suggested between
HRT use and family history. In a Cox regression model time to breast cancer
in relation to duration of HRT use was analysed adjusting for age at
menarche, age at menopause, age at first full term pregnancy, parity and age
at diagnosis. A significantly higher risk was seen for longer duration of HRT
use compared with never users. No increased risk is seen in women beyond 5
years after stopping HRT. There was no interaction between previous use of
oral contraceptives and later HRT use. Copyright
2001 Cancer Research Campaign |
Edward E.
Rylander, M.D.
Diplomat American
Board of Family Practice.
Diplomat American
Board of Palliative Medicine.