Endometrial (Uterine) Cancer and Natural Progesterone

Endometrial (uterine) cancer occurs in tissue sensitive to hormones made by the ovaries (estrogens and progesterone).

Generally, endometrial cancer develops during the pre-menopausal years when high levels of estrogen and low levels of progesterone are present. The only known cause of endometrial cancer is unopposed estrogen, though there may be other factors involved.

The initiation of normal cells turning into cancer cells is the same for both the breast or uterus and a man’s prostate gland. In these organs, cancer initiation is due primarily to estrogen dominance combined with lifestyle factors and/or toxic insults that predispose estrogen to become oxidised.

Estrogen is the hormone that stimulates cell proliferation, or the growing phase. In other words, estrogen causes cells to divide and multiply. Progesterone, on the other hand, is the hormone that stops growth and stimulates ripening. It induces cell maturation and programmed cell death (called apoptosis).

Although cells in different parts of the body may look and work differently, most repair and reproduce themselves in the same way. Normally, this division of cells takes place in an orderly and controlled manner. If, for some reason, the process gets out of control, the cells will continue to divide, developing into a lump which is called a tumour. Tumours can be either benign or malignant. Doctors can tell whether a tumour is benign or malignant by examining a small sample of cells under a microscope. This is called a biopsy.

Whilst not a cure for cancer, progesterone can dramatically decreases cell multiplication rates, providing women with a degree of protection against estrogen-driven cancers. Normal levels of progesterone in the body can, therefore, actually help protect you against some forms of cancer.

We know now that progesterone deficiency is linked to an increased risk of cancer. Uterine cancer, for example, is known to be caused by unopposed estrogen. That’s why women who have an intact uterus and take estrogen replacement therapy must also be given some form of progesterone to oppose estrogen and reduce this risk. This is generally given in the form of synthetic progestin (that carry health risks) designed to block estrogen effects, but differs considerably from the molecule that is human-identical progesterone.