The invention relates to a means of prevention and therapy of hormone-sensitive tumour tissue, especially for the prevention and/or inhibition of mammary carcinoma or prostate carcinoma. The composition according to the invention is characterised by comprising steroid hormones and aromatase inhibitors. This is preferably a triple combination of the steroid hormones oestriol (E3), progesterone and testosterone and an aromatase inhibitor. Another object of the invention is the use of the composition according to the invention for the manufacture of a drug for the prevention and therapy of hormone-sensitive tumours, preferably the mammary carcinoma or the prostate carcinoma. Areas of application of the invention are the pharmaceutical industry and the life sciences, especially medicine and medical technology,
