Best practice & research. Clinical obstetrics & gynaecology
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The potential for hormone therapy to cause cancer is the greatest fear for postmenopausal women considering hormone replacement therapy (HRT). Breast cancer is the most common female malignancy, for which HRT is one of many modifiable risk factors, often attracting disproportionate attention. Randomized controlled trials have confirmed that in postmenopausal women aged 50-59 years taking combined oestrogen and progestogen HRT over 5 years, there will be three extra cases of breast cancer per 1000 women. ⋯ The mechanism for these effects is not understood. Colorectal cancer and possibly lung and gastric cancers are reduced by the use of HRT. Apart from a slight increased risk of gallbladder disease and carcinoma with HRT, there are no data linking oestrogen or progestogen with any other malignancies.