A team led by researchers at the Mayo Clinic has developed a promising six-marker methylated DNA panel that can detect endometrial cancer with high sensitivity using self-collected vaginal fluid samples. The test could potentially reduce the need for invasive endometrial biopsies in patients with abnormal uterine bleeding.
Key Findings
The study, presented at the Society of Gynecologic Oncology 2025 Annual Meeting in Seattle, demonstrated 89% sensitivity for detecting endometrial cancer with 85% specificity. The test performed particularly well for higher-grade cancers: it achieved 100% sensitivity for grade 3 endometrioid tumors and 95% sensitivity for type II endometrial cancers.
"We successfully down-selected from a 19 gene candidate MDM pool to a 6-methylated DNA (MDM) panel that demonstrated high sensitivity for EC [endometrial cancer], increasing with grade and severity of disease," the researchers reported. "This panel detected EC in prebiopsied participants and in participants with atypical hyperplasia who had an underlying concomitant EC."
Clinical Background
Abnormal uterine bleeding (AUB) affects approximately 1.4 million women aged 18 to 50 in the U.S. annually, while 4% to 11% of postmenopausal women experience bleeding. Current ACOG guidelines recommend endometrial sampling for all women aged 45 and older with AUB and for younger women with endometrial cancer risk factors.
However, only 5% to 10% of AUB cases are caused by endometrial cancer or its precursors, meaning most endometrial biopsies return normal results. Additionally, office endometrial biopsies are known to cause significant pain for many patients.
Study Design and Methods
The researchers employed a three-step development pipeline:
- Discovery and technical validation using fresh frozen tissues
- Biological validation using independent archived FFPE tissues
- Clinical pilot using prospectively collected vaginal fluid samples
For the clinical validation, the team enrolled two cohorts:
- Cohort 1: Women who were at least 45 years old with AUB or at least 18 years old with Lynch syndrome
- Cohort 2: Women who were at least 18 years old with biopsy-confirmed endometrial cancer or atypical hyperplasia
The final analysis included 374 women with benign endometrium, 256 with endometrial cancer, 37 with atypical hyperplasia, and 27 with benign hyperplasia. Of the endometrial cancer cases, 61 (24%) were biopsy-naïve when the tampon sample was collected.
Participants self-collected vaginal fluid samples using tampons in a supervised clinical setting. DNA was extracted, bisulfite was converted, and samples underwent long-probe quantitative amplified signal assays testing with 19 methylated DNA markers and four reference genes.
Test Performance
The final 6-MDM panel achieved an area under the curve (AUC) of 0.93 (0.91-0.96). Sensitivity varied by histology type and grade:
- Overall endometrial cancer: 89%
- Type II cancers: 95%
- Type I cancers: 87%
- Endometrioid grade 3: 100%
- Endometrioid grade 2: 92%
- Endometrioid grade 1: 82%
- Atypical hyperplasia: 36%
- Benign hyperplasia: 22%
Future Directions
The researchers noted that while the current study had limitations, including restricted diversity among participants and limited numbers of certain histology types, the results support further development of this approach.
"A vaginal fluid-based test could impact initial clinical evaluation of AUB, in part, by reducing the number of unnecessary endometrial samplings," they concluded. "Subsequent studies are underway to further develop and validate a vaginal fluid-based test for EC that is generalizable to all elevated risk people with AUB."
The research was supported by Mayo Clinic Ovarian SPORE, V Foundation, Mayo Clinic Comprehensive Cancer Center, and Exact Sciences. Jamie Bakkum-Gamez, MD, the lead investigator, disclosed financial relationships with Exact Sciences, which provided research funding to Mayo Clinic and is listed as an inventor on intellectual property jointly owned by Mayo Clinic and Exact Sciences.
