Groundbreaking research has highlighted the potential benefit of adding the hormone progesterone to standard breast cancer treatments.

The international study resolves the controversy over whether progesterone is good or bad for women with oestrogen-receptor positive breast cancer.

Published in Science Advances, it reports that treatments aimed at the progesterone receptor could prolong life in women with oestrogen-driven breast cancer beyond the current standard treatments of tamoxifen or aromatase inhibitor medicines, which target the oestrogen receptor alone.

The study, led by Professor Geoffrey Greene at the University of Chicago, in collaboration with a team from the University of Adelaide, confirms and provides new insight into how progesterone receptors reprogram the actions of oestrogen receptor, with an overall “braking effect” on tumour growth.

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

“Use of progesterone treatment of breast cancer has raised considerable controversy because of past studies showing some negative effect of synthetic versions of progesterone used in hormonal therapy for postmenopausal women,” he says.

“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.”

The researchers also identified a new progesterone receptor targeting drug that not only opposes the action of oestrogen in breast cancers to halt tumour growth, but actually causes the tumours to regress.

Clinical trials start next year.

Last Reviewed: 27/06/2016

Reproduced with kind permission from