My doctor will not prescribe progesterone on the grounds that I have breast cancer

From our interpretation and that of the information provided in Dr John Lee’s publications, Dr Lee believes that perhaps doctors may not understand the distinction between these two very different receptors, and two very different hormonal roles in the body.

One receptor responds to estrogen, and one responds to progesterone. Hormones can be likened to chemical keys that turn vitally important metabolic locks in our cells. The turning of these locks stimulates activity within the cells of our brain, intestines, muscles, genital organs and skin. Without the hormonal keys the metabolic locks in our cells remain closed and the full potential of our cells is not realised.

Dr Lee maintains that the very fact that you have progesterone receptor sites is very positive. The progesterone receptors carry messages to breast cells to inhibit proliferation, >preventing growth of breast cancer cells. Estrogen, on the other hand, promotes cell proliferation, increasing the risk of breast cancer.

In the June 2001 edition of The John R. Lee M.D. Medical Letter Dr Lee wrote: “It is clear that unopposed estrogen (especially estradiol) is a causative factor in breast cancer. Other studies show that estrogen stimulates breast cell (and breast cancer cell) hyperplasia and dysplasia, whereas progesterone inhibits it. Still other studies show that estradiol stimulates the oncogene Bcl-2, whereas progesterone activates gene p53, which increases apoptosis and blocks the Bcl-2 carcinogenic effect.”

When the mechanism of action revealed by all these studies are understood, it becomes clear that estrogen dominance is a major factor in increasing the incidence of breast cancer, whereas progesterone prevents it.

In 1996, the British Journal of Cancer published a study by Dr Mohr et al. which found that the 18-year cumulative survival rate after breast cancer surgery in node-positive patients was twice as good (64 percent vs. 33 percent) among patients with normal progesterone levels than amount patients with low progesterone levels on the day of their breast surgery.

Professor Zava, responding in our August 2004 ‘Natural Progesterone Newsletter’, writes: “In cancer cells that contain progesterone receptors, progesterone should slow the growth of cancer and push it towards a more differentiated state. This progesterone-induced differentiation requires cell division so it is possible that progesterone was allowing the cancer cells to proliferate and differentiate (specialize) simultaneously. On the other hand it is possible that the breast cancer cells did not contain progesterone receptors, which would prevent them from responding to the anti-estrogenic actions of progesterone (ie, progesterone down-regulates estrogen receptors and desensitizes tissues to further growth-promoting actions of estrogens).

Most oncologists and general practioners that work with natural progesterone find that primary breast cancer, and breast cancer recurrences are less frequent in women using topical progesterone, but it does happen. My experience, in reviewing pathology reports from women who have developed breast cancer while using topical progesterone, is that they usually have tumors that do not contain progesterone receptors, or the receptors are very low.”

Women approach our website so distressed and uncertain following advice from their doctors that they cannot take progesterone because their progesterone receptors have tested ‘positive’. This is to imply that progesterone therapy will jepodise them further.
Dr John Lee does go into considerable detail in various articles of ‘The John R. Lee M.D. Medical Letter’ and, more recently, in his collaboration with David Zava, Virginia Hopkins titled ‘What Your Doctor May Not Tell You About Breast Cancer: How Hormone Balance Can Help Save Your Life’.