Uterine leiomyosarcoma (uLMS) is a rare, aggressive cancer in the uterus. It typically affects women between 45 and 60, often during perimenopause.

uLMS cases are usually discovered incidentally in women who undergo surgery to remove masses that are presumed to be benign uterine fibroids. Approximately one to five out of every 1,000 women with presumed fibroids are ultimately diagnosed with uLMS after the removed masses are tested. uLMS grows and metastasizes rapidly, carrying the worst prognosis among similar cancers called soft tissue sarcomas. Only one-quarter to three-quarters of patients survive for at least five years after their diagnosis, and as few as 10 percent of patients survive for at least five years if their disease has already metastasized when diagnosed.

The underlying causes of uLMS are highly complex and vary from case to case. They may involve irregularities in patients’ genomes, genome-regulating epigenetic attributes, metabolic pathways, or immune systems. This heterogeneity has made it challenging for researchers to narrow down a single target (or even a few targets) against which to develop therapies. Research is also hindered by the lack of robust model systems for uLMS, such as mouse models or cell cultures, which are typically used to help understand the disease or develop therapies.

uLMS treatment remains limited beyond surgical removal, which does not always eliminate all cancerous tissue. Conventional chemotherapy has shown only modest survival benefits in clinical trials. Radiation therapy is generally avoided due to the proximity of radiation-sensitive pelvic organs. Although other cancers have seen treatment progress thanks to targeted immunotherapies, there are currently no uLMS-specific therapies that have been approved by the US Food and Drug Administration.

Given the aggressive nature of uLMS, its poor prognosis, and the lack of effective treatments, there is an urgent need to understand the disease’s underlying biology and develop novel therapeutic approaches. To that end, Milken Institute’s Science Philanthropy Accelerator for Research and Collaboration has partnered with the Briger Foundation for Oncology Research and published a publicly available report, "Uterine Leiomyosarcoma: A Giving Smarter Guide". The report describes the current state of research, clinical practice, and treatment approaches for uterine leiomyosarcoma (uLMS) and identifies critical areas where philanthropy can significantly advance scientific knowledge and improve patient care.