Hormone replacement therapy increases risk of breast cancerBMJ 1997; 315 doi: https://doi.org/10.1136/bmj.315.7114.967e (Published 18 October 1997) Cite this as: BMJ 1997;315:967
- Jacqui Wise
The risk of breast cancer increases slightly in women using hormone replacement therapy (HRT), and this risk increases the longer the treatment is used, according to a thorough reanalysis of data on more than 160000 women.
Many individual studies of the effects of HRT on the risk of breast cancer have been published, but because results differ it has not been clear until now how great the increased risk might be and even if a risk existed at all.
Professor Valerie Beral, director of the Imperial Cancer Research Fund's Cancer Epidemiology Unit in Oxford, and her collaborators collated and analysed data on 52 705 women with breast cancer and 108411 women without breast cancer from 51 studies in 21 countries (Lancet 1997;350:1047-59). More than 900 of the women in the analysis had been taking HRT for 15 years or more.
The relative risk of having breast cancer diagnosed in-creased by a factor of 1.023 for each year of use among current users of HRT or those who had stopped using it in the previous four …