Estrogen-dependent are defined as all those forms of cancer whose onset and growth is promoted or in any case favored by the presence of estrogen hormones.
In particular, some forms of estrogen dependent tumors include:
- breast cancer
- cancer of the uterine endometrium (the outermost layer of the uterus)
- ovarian cancer
Hormone dependence is established by looking for the presence of specific hormone receptors in the excised tumor cells . Most but not all breast cancers , for example, are dependent on estrogen for cancer cell proliferation. Furthermore, the hormonal status of a tumor can vary over time: for example, early stage breast cancers are frequently hormone-dependent cancers, unlike advanced breast cancers which are not or less so.
The important role of estrogen hormones in the growth and extension of these tumor forms has prompted researchers to experiment with the anti-tumor efficacy of drugs capable of reducing the synthesis of estrogen and/or blocking its biological action, obtaining positive results especially in the treatment of breast cancer . Among these drugs are:
- Tamoxifen (e.g. Nolvadex , Tamoxifene AUR, Nomafen): prevents, through a mechanism of biological competition, the link between estrogens and their receptor; it is therefore used in the treatment of breast cancer in women of childbearing age , in which the aforementioned hormones are mainly produced by the ovary;
- Exemestane (e.g. Aromasin ), Anastrozole ( Arimidex ): by blocking the activity of aromatase (an enzyme that converts androgens into estrogens), they are indicated to treat estrogen-dependent cancers in post- menopausal women , in which the ovarian estrogen synthesis is minimal and estrogens are produced in minimal quantities in the periphery, especially in adipose tissue ( obese women run, for example, a greater risk of developing endometrial and breast cancer ).
At the same time, the important role of estrogen hormones in the growth and extension of these tumor forms explains the need – in the case of an already manifest estrogen-dependent tumor form or family/genetic predisposition to it – to avoid taking long-term use of drugs or preparations that can enhance the synthesis or activity of estrogen hormones:
- combined birth control pill , vaginal ring , birth control patch
- hormone replacement therapy in menopause
- androgenic drugs, anabolic steroids
- prudence in the use of some phytotherapeutic preparations containing phytoestrogens , such as soy , black cohosh and red clover , or essential oils containing compounds with estrogenic activity (e.g. essential oil of fennel , anise , sage or moscatella grass)
Late menopause , especially if associated with precocious puberty , also represents an important risk factor for the development of estrogen-dependent tumors, especially breast cancer, since the body is exposed to endogenous estrogens for longer . It should be noted that the removal of the ovaries and fallopian tubes in still fertile women can stop or slow the growth of breast and ovarian tumors that need estrogen to grow , although it is obviously a not so immediate therapeutic choice .
With regard to colon cancer and prostate cancer , estrogen hormones are sometimes used in therapy as an adjuvant to promote tumor regression or increase patient survival, as they seem to have a positive effect in this sense.
The information illustrated in the article is naturally of a general nature, in fact it is up to the doctor to establish the estrogen-dependent nature of a tumor and the most suitable medical therapy. For example, experimental evidence has shown that the administration of estrogen alone to hysterectomised women (who had previously had their uterus surgically removed ) did not lead to any increase in the incidence of breast cancer, or even prevented its onset. Even in women with an intact uterus, estrogen-only hormone replacement therapy does not seem to increase the incidence of breast cancer; unfortunately it tends to raise the risk of endometrial cancer, so it is generally preferred to associate a progestogen (natural or synthetic), although the combination of the two increases the risk of breast cancer.
Furthermore, hormone replacement therapy appears to significantly reduce the incidence of colon cancer , while the use of combined contraceptive pills appears to represent a protective factor against ovarian cancer.
In general, the relationship between hormonal therapies and the risk of estrogen-dependent forms of cancer remains a rather controversial topic, on which the last to pronounce can only be the doctor treating the patient.