[Hormone replacement and breast carcinoma]

This review discusses the effect of Oestrogens, Progestagens, Tibolone, Raloxifene and Phytooestrogens in postmenopausal women on the breast. Epidemiological statisticians are only speaking of a clinical significance if the relative risk is half (< 0.05) or doubled (> 2.0). All published data from observational studies or from important meta- and reanalyses concerning the relative risk of breast cancer in women using postmenopausal hormone therapy are within these limits and clearly below the risk observed in young smokers. The relative risk for breast cancer observed in the Womens Health Initiative (WHI) stays within these limits too, in women treated by a fix Oestrogen-Progestagen combination. However, in the WHI, there was no increase of the relative risk for breast cancer in women using oestrogens alone. The risk for breast cancer rises in parallel to the duration of the hormone treatment. The risk for hormone users to suffer from breast cancer does not increase earlier than 4-5 years after the start of the therapy. An important reanalysis reports, that after 5 years of hormone use, a breast cancer is diagnosed in 2 additional women out of 1000 (47 instead of 45 women). The absolute risk should be indicated in addition to the relative risk because, for non-specialists, the exclusive indication of the relative risk might be misleading. Following the results from the WHI and from some other, older studies, the relative risk for breast cancer might be higher in women taking an oestrogen-progestagen combination than in women using oestrogens alone. Experimental and preliminary clinical data on Tibolone and Raloxifene do not show a negative effect on breast tissue. However, if Tibolone and Raloxifene as well as Phytooestrogens possess a protective activity remains open because prospective randomized long-term clinical studies are still missing.