Author/Editor		Beral, V; Calle, EE; Heath, CW; Coates, RJ; Liff, JM; Franceschi, S; Košmelj, K; Primic-Žakelj, M; Ravnihar, B; Stare, J
Title		Breast cancer and hormone replacement therapy: collaborative reanalysis of data from 51 epidemiological studies of 52 705 women with breast cancer and 108 411 women without breast cancer
Type		članek
Source		Lancet
Vol. and No.		Letnik 350
Publication year		1997
Volume		str. 1047-59
Language		eng
Abstract		Background. The Collaborative Group on Hormonal Factors in Greast Cancer has brought together and reanalysed about 90% of the worldwide epidemiological evidence on the relation between risk of breast cancer and use of hormone replacement therapy (HRT). Methods. Individual data on 52705 women breast cancer and 108411 women without breast cancer from 51 studies in 21 countries were collected, checked, and analysed centrally. The main analyses are based on 53865 postmenopausal women with a known age at menopause, of whom 17830 (33%) had used HRT at some time. The median age at first use was 48 years, and 34% of everusers had used HRT for 5 years or longer. Estimates of the relative risk of breast cancer associated with the use of HRT were obtained after stratification of all analyses by study, age at diagnosis, time since menopause, body-mass index, parity, and the age a woman was when her first child was born. Findlings. Among current users of HRT or those who ceased use 1-4 years previously, the relative risk of having breast cancer diagnosed increased by a factor or 1-023 (95% CI 1-011-1.036; 2p=0.0002) for each year of use; the relative risk was 1.35 (1.21-1.49; 2p=0.0001) for women who had used HRT for 5 years or longer (average duration of use in this group 11 years). This increase is comparable with the effect onbreast cancer of delaying menopause, since among never-users of HRT the relative risk of breast cancer increases by a factor of 1.028 (95% CI 1.021-1.034) for each year older at menopause. 5 or more years after cessation of HRT use, there was no significant excess of breast cancer overall or in relation to duration of use. These main findings did not vary between individual studies. (Abstract truncated at 2000 characters.)
Descriptors		BREAST NEOPLASMS ESTROGEN REPLACEMENT THERAPY MIDDLE AGE POSTMENOPAUSE BODY MASS INDEX RISK FACTORS TIME FACTORS