المتخصصون في المجالات الطبية

Jan. 09, 2024

A Mayo Clinic-led study has made significant strides toward timelier endometrial cancer (EC) detection, improving the likelihood of cure due to disease identification at an early stage. Gynecologic Oncology published these findings in the July 2023 issue.

"This was a robust molecular discovery of methylated DNA markers particular to the gene's promoter region; these markers were not present in benign endometrium," says Jamie N. Bakkum-Gamez, M.D., a gynecologic oncologist at Mayo Clinic in Rochester, Minnesota.

Study design

In 2004, Cancer Epidemiology, Biomarkers and Prevention published an Austrian study that used tampons to distinguish EC and benign conditions. In 2015, Dr. Bakkum-Gamez and colleagues set out to replicate the 2004 study.

In the study, Dr. Bakkum-Gamez says she and colleagues were on a hunt to determine which genes might be methylated in EC, as methylation is a known hallmark of cancer.

"We intentionally went into this as a discovery approach to find these particular markers with detailed sequencing," she says.

In the study's discovery phase, the investigators performed reduced representation bisulfite sequencing to pinpoint differentially methylated regions (DMRs). They used samples of DNA from frozen EC, plus benign endometrium (BE) and cervicovaginal tissues. They then used receiver operating characteristic discrimination, methylation-level fold changes between cancers and controls, and absence of CpG methylation to select potential DMRs. Using quantitative methylation-specific PCR (qMSP) on independent EC and BE formalin-fixed, paraffin-embedded tissues, the investigators performed methylated DNA marker (MDM) validation.

Next, the investigators examined vaginal fluid self-collected with an over-the-counter, unscented tampon. They identified EC though biopsy prior to endometrial sampling or hysterectomy.

Regarding this choice of assay tool, Dr. Bakkum-Gamez says, "We knew that a high proportion of women use tampons. We wanted a tool familiar to women."

All study participants had experienced abnormal uterine bleeding at age 45 or older, or postmenopausal bleeding at any age. Investigators used qMSP to identify EC-associated MDMs through an assay of vaginal fluid DNA. To determine the predictive probability of disease presence, the investigators used random forest modeling. They 500-fold, in-silico cross-validated the results.

Study findings

In the complete potential MDM set, 33 met in-tissue performance criteria. In the tampon pilot portion of the study, the investigators frequency-matched 100 patients with EC by menopausal status and collection date via tampon to 92 BE controls. A 28-MDM panel highly discriminated between EC and BE with 96% specificity and 76% sensitivity. In phosphate-buffered saline-ethylenediamine tetraacetic acid tampon buffer, the panel demonstrated 96% specificity and 82% sensitivity.

Importance of the findings

Dr. Bakkum-Gamez explains the significance of these EC detection findings as follows:

• Earlier diagnosis. She says earlier diagnosis leads to better survival for women with EC. This test is being developed with one goal being earlier detection of EC versus later in the cancer's development, improving the chance for a cure.
• Early signs. The investigators discovered that a gradient of increasing methylation occurs between the precursor to EC — endometrial hyperplasia — and EC. This should allow for methylated DNA markers to be leveraged in the detection of precancerous lesions such that interventions can occur to prevent EC development.
• Solving for pain. The tampon method of EC detection would ideally provide an alternative for office endometrial biopsy, an often-painful abnormal bleeding investigation procedure in which a healthcare professional uses a long, straw-like instrument introduced through the cervix to obtain endometrial tissue. Though useful, this technique can cause excruciating pain for the patient.
• Providing an EC test. No minimally invasive EC diagnostic or screening test exists. Though some may think a PAP smear is used for EC detection, this is incorrect, says Dr. Bakkum-Gamez. A tampon-based test introduces a novel, less invasive EC diagnostic option.
• Offering a comfortable test setting. The investigators also wanted a private, familiar environment for women to test for EC. The tampon-based assay is being designed to be performed at home.

Next steps in EC and other GYN cancer early-detection research

Mayo Clinic and Exact Sciences have now licensed over 500 EC markers identified in this study.

One EC detection assay step that Dr. Bakkum-Gamez and colleagues are still finalizing is how long women would wear the tampon for fluid collection. In the study published in Gynecologic Oncology, the average time was 40 minutes.

Dr. Bakkum-Gamez says the ultimate cost of the tampon-based detection assay depends on how test development unfolds. However, her goal is a no-cost or an affordable out-of-pocket cost for women to use this at-home test.

Though she calls the clinical pilot data very promising, Dr. Bakkum-Gamez indicates the need for larger tampon-based MDM assay studies. She hopes the assay will be available to the public in a couple of years. While this assay is for women who are symptomatic, she hopes screening will be available in the future for women who are asymptomatic.

The Mayo Clinic research team also is looking into early detection for a broader array of GYN cancers. Currently, the investigators are furthering the research with the tampon-based detection assay. They are leading a pan-gynecologic cancer detection test clinical trial: Leveraging Methylated DNA Markers (MDMs) in the Detection of Endometrial Cancer, Ovarian Cancer, and Cervical Cancer. The group is testing vaginal fluid for the presence of cancer-specific methylated DNA markers identified for EC, ovarian cancer and cervical cancer as well as high-risk human papillomavirus. The study is accruing patients in Minnesota, Florida and other sites and is in the process of activation in Arizona and multiple other locales.

"Ideally, I would love to bundle testing together so we could pick up GYN cancers such as ovarian cancer, cervical cancer and others all at the same time," says Dr. Bakkum-Gamez, indicating she would like to explore this concept further.

Financial disclosures. John B. Kisiel, M.D., Jamie N. Bakkum-Gamez, M.D., Douglas W. Mahoney, M.S., and William R. Taylor, M.S., are inventors of Mayo Clinic intellectual property that is licensed to Exact Sciences (Madison, Wisconsin) and may receive royalties, paid to Mayo Clinic. Seth W. Slettedahl, M.S., Xiaoming Cao, Patrick H. Foote, Kelli N. Burger, Calise K. Berger, Maria C. O'Connell, Karen A. Doering, M.B.A., CCRP, Maureen A. Lemens, C.C.R.C., Ann L. VanOosten and Julie K. Staub are supported under a contract between Mayo Clinic and Exact Sciences. Mark E. Sherman, M.D., has received collaborative research funding supported by Exact Sciences.

For more information

Bakkum-Gamez JN, et al. Detection of endometrial cancer using tampon-based collection and methylated DNA markers. Gynecologic Oncology. 2023;174:11.

Fiegl H, et al. Methylated DNA collected by tampons — A new tool to detect endometrial cancer. Cancer Epidemiology, Biomarkers and Prevention. 2004;13:882.

Erickson BK, et al. Detection of somatic TP53 mutations in tampons of patients with high-grade serous ovarian cancer. Obstetrics & Gynecology. 2014;124:881.

Mayo Clinic. Leveraging Methylated DNA Markers (MDMs) in the Detection of Endometrial Cancer, Ovarian Cancer, and Cervical Cancer (ECHO). Clinicaltrials.gov.

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