Progesterone could slow breast cancer growth in 50% of patients

There are around 50,000 new cases of breast cancer each year in the United Kingdom and around half could potentially benefit from this finding, according to the researchers.

“One in eight Australian women will be diagnosed with breast cancer in their lifetime and seven women die from the disease each day in Australia”, says Professor Tilley.

One of the most successful breast cancer drugs, tamoxifen, bungs up the oestrogen receptor.

They found that progesterone appears to slow cancer cell growth by changing estrogen receptor interaction with DNA.

Around 75% of patients with breast cancer are positive for estrogen receptors (ER+) and around 75% of those are positive for progesterone receptors (PR+), so the researchers suggest their findings could benefit around half of breast cancer patients.

“By taking this sponge, which contains a number of factors that promote viability of the cells, the tumour cells seem to like this and their viability and growth is maintained over a period of time in the laboratory”.

But another molecule, the progesterone receptor, is also important.

Experts have always been puzzled by the fact that breast cancer patients whose tumours have progesterone receptors – molecules sensitive to the hormone – often have a better outlook. Until now, the reason why was unknown. ‘This research helps explain why some breast cancer patients have a better outlook, ‘ Carroll said.

They then grew breast cancer cells with and without progesterone and found when the progesterone receptor is activated, it redirects the estrogen receptor to different DNA regions. Tests showed that mice given progesterone and tamoxifen had breast tumours only half the size of those given the drug on its own. Details of the study are reported in Nature.

Hormones play a huge role in breast cancer.

“Crucially, it provides a strong case for a clinical trial to investigate the potential benefit of adding progesterone to drugs that target the oestrogen receptor, which could improve treatment for the majority of hormone-driven breast cancers”, Carroll added. Emma Smith at Cancer Research United Kingdom, which funded the study, said that if progesterone is found to work in human trials, the hormone could particularly help women whose tumours have become resistant to standard drugs.

A great new study says implies that half of breast cancer patients could benefit from the implementation of the female hormone progesterone as part of their treatment.