Scientists are beginning to understand why some breast cancers become more dangerous after menopause, especially for women who have obesity. New research suggests that a little‑known hormone that becomes more common after menopause may help explain this increased risk.
The work comes from researchers at Georgetown University and focuses on the most common type of breast cancer found in older women. The study highlights how changes in hormones after menopause can create conditions that allow certain cancers to grow faster and become harder to treat.
Breast cancer is one of the most common cancers affecting women around the world. Among its different forms, one type called estrogen receptor‑positive breast cancer, or ER‑positive breast cancer, is the most common after menopause.
In this type of cancer, tumor cells grow in response to estrogen, a hormone that normally helps regulate many functions in the body.
Dr. Joyce Slingerland, a cancer researcher at Georgetown University’s Lombardi Comprehensive Cancer Center, says that postmenopausal women with obesity face a particularly high risk.
Studies show that they are not only more likely to develop ER‑positive breast cancer, but they are also two to three times more likely to die from it compared with women of lower weight.
This issue is becoming more important as obesity rates continue to rise. Researchers estimate that by the end of this decade, nearly half of all women in the United States may be living with obesity. Understanding why obesity makes some cancers more aggressive could help doctors develop better ways to treat and prevent the disease.
The key hormone involved in the new research is called estrone. Estrone is a type of estrogen that becomes the main form of estrogen in the body after menopause. Before menopause, the ovaries mainly produce a different form of estrogen called estradiol.
Although estradiol and estrone are chemically similar, they behave quite differently inside the body. Estradiol has several protective effects and can help control inflammation, which is the body’s natural response to injury or infection.
Inflammation is helpful for short periods, but when it continues for a long time it can damage tissues and contribute to diseases such as cancer.
After menopause, levels of estradiol drop sharply. At the same time, estrone becomes the dominant estrogen in the body. Unlike estradiol, estrone is produced mainly in fat tissue rather than in the ovaries.
This means that women with more body fat tend to have higher levels of estrone. In fact, researchers have found that estrone levels in fat and breast tissue can be two to four times higher in women with obesity.
Dr. Slingerland’s research shows that estrone does not simply replace estradiol after menopause. Instead, it behaves in a very different way that may promote cancer growth.
Her team discovered that estradiol can help calm inflammation by blocking certain proteins that trigger inflammatory signals. Estrone, however, appears to do the opposite. It works together with inflammatory proteins and turns on genes that keep inflammation active.
Long‑lasting inflammation is known to create conditions that help cancer cells survive and grow. It can also help tumors spread to other parts of the body. Because estrone increases inflammation, it may help explain why breast cancer becomes more aggressive in some postmenopausal women.
Earlier studies from the research group also showed that estrone can activate genes that push cells toward cancer development. It can also turn on processes that help cancer cells move and spread.
Experiments in mice provided further evidence. In those studies, breast tumors exposed to estrone grew faster and spread more widely than tumors exposed to estradiol.
The researchers also found signs that estrone might weaken the immune system’s ability to recognize and destroy cancer cells. If the immune system becomes less effective, tumors may grow more easily without being stopped by the body’s natural defenses.
Because estrone is produced in fat tissue, reducing body fat could help lower estrone levels and the inflammation it creates. This idea has led scientists to consider whether modern weight‑loss medications might one day help improve cancer treatment.
In particular, researchers are interested in drugs known as GLP‑1 receptor agonists. These medications, including drugs such as Ozempic and Wegovy, have become widely known for helping people lose weight by reducing appetite and improving metabolism.
If these drugs reduce body fat, they may also lower estrone levels in the body. In theory, this could reduce inflammation and make the environment around tumors less favorable for cancer growth.
Lifestyle changes such as healthier diets and regular physical activity can also help reduce body weight and inflammation. However, many people find it difficult to maintain large weight changes for long periods of time. Medications that support weight loss might therefore offer an additional option for patients.
The findings of this research were published in the journal Nature Reviews Endocrinology. The work suggests that doctors may need to think differently about breast cancer treatment in postmenopausal women with obesity.
Instead of focusing only on the tumor itself, future treatments may also need to address the hormonal and inflammatory environment created by fat tissue.
Although more studies are still needed, including clinical trials in patients, the research highlights a promising new direction. By understanding the role of estrone and inflammation, scientists may be able to develop new strategies to slow cancer growth and improve survival for many women.
If you care about breast cancer, please read studies about how eating patterns help ward off breast cancer, and soy and plant compounds may prevent breast cancer recurrence.
For more health information, please see recent studies about how your grocery list can help guard against cancer, and a simple way to fight aging and cancer.
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