Experimental Vaginal Swab Aims to Spare Some Women From Painful Endometrial Cancer Biopsies

A woman past menopause notices bleeding that shouldn't be there. The standard path from that moment runs through a transvaginal ultrasound, in which a probe measures the lining of the uterus, and often through an endometrial biopsy, in which a thin tube is passed into the uterus to scrape out a small sample of tissue. Both procedures can hurt. A California company called PinkDx is testing whether a vaginal swab could, for some of these women, replace the biopsy as the first step.

The test is being studied at 16 sites across the United States, according to The Washington Post. It is intended for women who already have symptoms, such as bleeding after menopause, rather than for routine screening of healthy women. Endometrial cancer begins in the lining of the uterus, and the swab is built on a simple idea: dying cancer cells in the uterus shed fragments of genetic material that carry the tumor's fingerprint. Some of those fragments drift down into the vagina, where a clinician can collect them with a swab and send them to a lab.

The biopsy has a practical weakness beyond the pain. In women past menopause, it fails to collect enough tissue about 30% of the time, The Post reported. Sometimes the uterine lining is too thin to sample. Sometimes the cervix is too narrow for the instrument to pass. A failed biopsy leaves a woman with symptoms and no answer.

The need is growing. Endometrial cancer death rates are climbing, partly because aggressive forms of the disease are becoming more common. Dr. June Hou, a gynecologic oncologist at Columbia University Irving Medical Center in New York City, is leading the PinkDx study at her institution. Of all cancers, she told The Post, this is one with more cases diagnosed every year.

The evidence so far is thin. In an early test of 27 women who were undergoing hysterectomy, PinkDx detected the tumor signal even in swabs taken from the vaginal opening. Dr. Nicolas Wentzensen, deputy director of the Clinical Genetics Branch at the National Cancer Institute, told The Post that this first effort was very small, and that its findings need to be confirmed in a larger, independent group.

That larger test is under way. The current study plans to enroll about 3,000 women and is expected to finish this year. Company officials told The Post that early results are on target. The company has set two benchmarks: the swab must catch at least 90% of cancers, and it must correctly rule out cancer in at least half of the women who don't have it, which limits false alarms.

If those numbers hold, Wentzensen said, the swab could serve as a first step that spares "half of the population from doing the biopsy." The limits are clear, though. Women who test positive would likely still need a biopsy to confirm the result. Women who test negative should still follow up with their doctor to look into other causes of their symptoms.

The regulatory route is relatively short. Because PinkDx plans to run the test only in its own lab, it does not need approval from the U.S. Food and Drug Administration, The Post reported. The company instead expects to finish certification with the Centers for Medicare & Medicaid Services by early 2027, which would let the swab reach patients by mid-2027. The thing to watch is the 3,000-woman study's results, and whether they clear the 90% and 50% thresholds.