[Drugs and cancer risk: the example of THM]

Estrogen-progestagen menopausal hormone therapy (MHT), indicated for the treatment of troublesome climacteric symptoms, is recognized as carcinogenic to humans. We present the available epidemiologic evidence concerning its link with the risks of breast, ovarian, endometrial and colorectal cancers. While results on cancers other than breast cancer are still imprecise or even contradictory, there is a clear increase in breast cancer risk associated with the use of estrogen-progestagen MHT. Attempts to play down in the public opinion the risk of breast cancer associated with these treatments evoke a better prognosis of tumors induced by MHT, the fact that MHT would only accelerate the presentation of pre-existing breast tumors that would otherwise have appeared latter, or that MHT would be devoid of risks when initiated close to menopause onset. We show that these assertions are not supported by the available epidemiological evidence.