Researchers Support Use of “Harmful” Synthetic Hormone in Breast Cancer Patients

Progestins have gotten bad rap, experts say

An international team of researchers is tackling the controversy surrounding a “harmful” hormone, arguing that it could be a game changer in the fight against recurring breast cancers that are resistant to standard treatments. The controversy centers on the effects in women of the naturally occurring steroid hormone progesterone compared with those of synthetic forms (i.e., progestins) designed to mimic its actions.

Some progestins have been linked with an increased risk of breast cancer when used in menopausal hormone therapy, leading to concerns in the scientific community about the safety of these drugs.

In an article published in Nature Cancer Reviews, however, an international team has found that progesterone does not increase breast cancer risk when used in menopausal hormone therapy. Indeed, progesterone may have an important role to play in the safe and effective management of recurring breast cancer, the team says.

“Breast cancer arises because of abnormal hormone activity, with about 75% of these cancers being driven by the estrogen receptor. Unfortunately, despite good initial responses in many women, drug resistance is common, usually leading to a recurrence and lethal spread of the disease,” said lead author Professor Wayne Tilley of the University of Adelaide in Australia.

“Moreover, current hormonal treatments that target the estrogen receptor in breast cancer, especially specific inhibitors that block estrogen production, can markedly impact quality of life, often leading women to stop taking the drugs or change their treatment.”

Tilley said that the team’s recent studies, including research already published in Nature, suggest that a safe way of improving treatment—without having a deleterious effect on quality of life—does exist, through the use of natural progesterone and certain other progestins.

“There is a natural ‘crosstalk’ between estrogen and progesterone receptors that we strongly believe can be exploited,” he said. “In particular, progesterone can reprogram estrogen action in the breast in a way that results in estrogen receptor action improving breast cancer outcomes. Because of this unique interaction of the two natural female sex hormones in the breast, we see great potential benefits in adding progesterone to existing drugs that target the estrogen receptor, thereby helping to switch off the growth of cancer cells.”

The researchers believe their new paper will have a global impact on clinical, scientific, and public opinion regarding the relative risks and benefits of using progesterone and certain progestins to treat women with breast cancer. “Ultimately, we hope this work will eventually result in saving women’s lives,” Tilley said.

The real proof will come from two new clinical trials being conducted by the international team. Patients will be recruited for the studies in the United Kingdom early next year.

Source: University of Adelaide; December 9, 2016.