Estrogen’s Role in Promoting Tumor Growth and Potential Cancer Treatment

Estrogen, a female hormone, has been found to promote the growth of breast cancer and other tumors by weakening immune cells that help suppress tumors.

The research team envisions that anti-estrogen drugs could be applied to cancer treatment.

On the 28th (local time), Professor Donald McDonell’s team from the Cancer Institute of Duke University published in the scientific journal Science Advances the results of experiments on mouse models of breast cancer and melanoma which demonstrated that estrogen weakens the ability of the immune system to attack tumors and have an immunotherapeutic effect has also been revealed to be decreased.

Breast Cancer and the Importance of Immunotherapy

Breast cancer is one of the most common cancers in women. Triple-negative breast cancer, which lacks the estrogen receptor (ER), progesterone receptor (PR), and epidermal growth factor receptor 2 (HER2), metastasizes to the brain and lungs more often than other breast cancers and has a 5-year survival rate of only 12%.

Professor McDonell said: “Treatment of triple-negative breast cancer has significantly improved with the advent of immunotherapy, but in many cases the effect is not good. The main aim of this research is to develop a method to increase the antitumor activity of immunotherapy.”

The Role of Eosinophils in Tumors

Eosinophils have recently been found to play an important role in tumors, and tumor-associated eosinophilia (TATE) has been shown to be associated with a better prognosis in cancer patients, including colon cancer, esophageal cancer, stomach cancer, oral cancer, melanoma, and liver cancer.

Experiments in mouse models of breast cancer and melanoma demonstrated that estrogen promoted the growth of estrogen receptor-negative breast tumors and melanoma tumors that do not depend on estrogen receptors for growth by reducing the number of eosinophils and associated eosinophilia to the tumor (TATE).

Potential Application of Anti-Estrogen Drugs

In contrast, it was found that in mice given anti-estrogen drugs, estrogen receptor signaling was suppressed, improving the effectiveness of immunotherapy and slowing tumor growth.

“These findings show that estrogen plays an important role in the action of eosinophils and the regulation of TATE,” Professor McDonell said. “This suggests the potential application of anti-estrogen drugs to improve the efficacy of immunotherapy for different types of cancers.”

He added: “Based on these findings, we are planning a clinical trial of an anti-estrogen drug called “lasopoxifene” for patients with triple-negative breast cancer.”