Estrogen fuels cancer growth

Estrogen fuels cancer growth

bioidentical progesterone opposes cancer growth

Bioidentical progesterone opposes cancer growth

The role of progesterone receptor in breast cancer

Breast cancer survival could be improved by adding progesterone

There is some exciting research in breast cancer treatment I want to share with you.

If you are concerned about breast cancer, are currently undergoing treatment, or want to take steps to look after your breasts, this is good stuff!

An international study including researchers from the University of Adelaide shows the potential benefit of adding bioidentical progesterone to standard breast cancer treatments.

The role of estrogen in driving tumour growth in breast cancers is well established, but the role of progesterone is the topic of much controversy.

The study published in June 2016 and led by Professor Geoffrey Greene at the University of Chicago in collaboration with Professor Tilley at the University of Adelaide employed a special technique for modelling breast cancer developed by the Adelaide group. This model allows researchers to test potential new treatments directly on breast cancer tissue donated by patients.

Building on earlier work by the University of Adelaide and the Cancer Research UK Cambridge Institute, the new 2016 study independently confirms and provides new insight into how progesterone receptors reprogram the actions of estrogen receptor, with an overall “braking effect” on tumour growth.

“We have known for some time that the progesterone receptor plays an important role in breast cancer, but gaps in our knowledge of the function of this receptor in breast tumours have limited the potential to develop new treatments,” says Professor Tilley. “This independent study provides important preclinical validation for initiation of clinical trials testing progesterone in combination with current standard-of-care therapy.

“Use of progesterone for treatment of breast cancer has raised considerable controversy because of past studies showing some negative effects of synthetic versions of progesterone used in hormonal therapy for postmenopausal women. In our studies, we are using natural progesterone, or forms of this hormone that are biologically identical to the natural hormone, and testing it on breast cancer tissue taken from women with cancer.”

Professor Wayne Tilley says the study provides important preclinical validation for the start of clinical trials in 2017 testing progesterone in combination with current standard-of-care therapy.


What have we been saying all these years …?

If you’ve been following my blog for any length of time, you will have seen Q&A articles like this one from Leisa and Angi where we deep dived into the conversation with hormone expert Dr. David Zava, Ph.D., Co-Author of What Your Doctor May Not Tell You About Breast Cancer on the carcino-protective properties of bioidentical progesterone in hormone regulation and breast health.

In this space, we’ve explored how breast cancer cells that do not contain progesterone receptors 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).

The following is an extract from Professor Zava’s blog dated December 2010:

Most breast cancers (60-70%) present with receptors for both estrogens and progestogens (ER+/PR+), and about 20-30% fall into the other categories (about 10-15% are ER-/PR-). This is an area I would consider myself somewhat of an expert in as I helped develop the technology for detecting ER and PR in breast cancers in the late 1970’s, ran three different breast cancer testing laboratories that did this type of testing (from the mid 1970s to mid 1990s), and am published extensively using breast cancer cell lines and human clinical samples post breast cancer surgery.

“Luteal levels of progesterone (>10ng/ml) need to be achieved for progesterone to act as an estrogen antagonist to prevent estrogen from excessively stimulating breast cell proliferation. Women who have an excess of estrogen relative to progesterone (low progesterone/estradiol ratio), are more likely to have atypical benign breast disease that is at increased risk of developing into breast cancer (Sitruk-Ware et al J Clin Endocrinol Metab 44, 771, 1977). Low endogenous luteal progesterone levels in premenopuase women (much more prevalent in peri-menopausal woman) have also been associated with increase breast cancer risk (Micheli et al Int J Cancer 112, 312-318, 2004).

“It is unfortunate that in spite of all the science and clinical studies behind it, only one small study (Plu-Bureau G et al Cancer Detect Preve 23(4), 290-296, 1999) that I am aware of looked at the risk of breast cancer with TOPICAL progesterone in a manner similar to what Dr. John Lee recommended for progesterone use (10-30 mg topical progesterone daily). In that study, they showed the risk to be reduced by half (0.5) in those using topical progesterone for 3 years or more. This is entirely consistent with the notion that when progesterone is delivered topically at a physiological level, it is protective.”.Dr Zava,, USA


The good news shared with you today is that Cambridge-based Cancer Research UK researcher Dr Jason Carroll and his team, and their colleagues at the University of Adelaide in Australia are creating a paradigm shift that could potentially revolutionize breast cancer treatment, and help more women survive this disease.

I believe, as I have done since 1996 when I first stumbled on the late Dr John’s Lee’s work, that progesterone supplementation can save lives. I believe progesterone offers a form of ‘insurance’ against the ravages of breast cancer. I believe every woman over 35 ought to consider introducing progesterone cream into her breast health program.

In love & appreciation,

Catherine P Rollins, Founder & CEO
Catherine P. Rollins
Founder & CEO

Ethically Supporting Women’s Choice of BHRT Since 2001