
For millions of women, uterine fibroids are a painful condition they manage daily. Not only do they cause significant pain, but they can also lead to heavy periods and infertility. Now, researchers are investigating whether a medication commonly used in breast cancer treatment — letrozole — could offer another option for managing these noncancerous growths.
The PLUM Study, led by researchers at the University of California, San Francisco, is testing whether letrozole can reduce fibroid-related symptoms and improve overall quality of life. The trial is expected to enroll 140 participants.
Letrozole falls under a class of drugs known as aromatase inhibitors. It’s often used to treat certain hormone-sensitive breast cancers by reducing the amount of estrogen the body makes. It is also used for fertility treatments such as intrauterine insemination (IUI) or even preserving fertility for women with breast cancer.
That estrogen-lowering effect is worth studying, since uterine fibroids respond to hormones. The study will compare 2.5 milligrams (mg) of letrozole to a placebo to determine whether the medication can improve symptoms and potentially reduce fibroid and uterine size.
Although the study is investigating letrozole as a potential fibroid treatment, it doesn’t mean the drug has already been proven effective for this purpose.
RELATED: Why Black Women Need to Be Included in Fibroid Clinical Trials
The study is currently accepting eligible participants at UCSF in San Francisco. Other participating sites include Mayo Clinic in Rochester, Minnesota, and the University of Mississippi Medical Center in Jackson, Mississippi; UCLA and Duke are listed as sites but have not started recruiting.
Participants must be ages 21 to 53 and not going through menopause. They must have fibroids that have been confirmed through an ultrasound or MRI within the last 24 months and have experienced fibroid-related symptoms for at least three months.
Those symptoms can include:
There are also important exclusions. For example, women cannot participate if they are currently pregnant or breastfeeding, have recently been pregnant or breastfeeding, or plan to become pregnant during the study. Certain fibroid sizes and types, severe anemia, osteoporosis, a history of breast cancer, and some medications or medical conditions can also make someone ineligible.

Fibroids are extremely common, affecting up to 70 to 80 percent of women by age 50, according to UCSF researchers. Yet treatment can be complicated, particularly for women who want to preserve fertility or avoid invasive procedures.
Black women face a disproportionate burden from uterine fibroids. Research shows they are more likely to develop fibroids at younger ages and experience more severe disease, including larger or multiple tumors. Black women also report greater symptom severity and are more likely to undergo procedures such as hysterectomy or myomectomy.
The reasons for these disparities are not fully understood. Researchers are investigating potential genetic, hormonal, environmental, and social factors. Because fibroids can affect menstrual health, fertility, physical activity, and quality of life, expanding treatment options and ensuring Black women are represented must be prioritized.
These disparities make research into additional medication-based approaches particularly important. A successful nonsurgical treatment could potentially give patients — particularly Black women — another tool for managing symptoms and improving quality of life.
RELATED: The Future of Fibroid Treatment: What Clinical Trials Are Studying Right Now
The PLUM Study began in 2024 and is expected to continue through 2028, according to the current UCSF study listing. Because the trial is still underway, researchers have not yet reported whether letrozole is effective for treating fibroids.
Women interested in participating can contact the study team to learn more and determine whether they qualify.

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