Pap test fluids used in gene-based screening test for two gyn cancers

PapSEEK detects mutations in DNA that have been identified for specific cancers sooner. Earlier detection of cancer could lead to earlier treatment and potentially better outcomes for patients.

The test uses cervical fluid samples to look for mutations in 18 genes, which are highly or commonly mutated in endometrial or ovarian cancers, and aneuploidy, the presence of abnormal numbers of chromosomes in cells. The researchers said their results showed the potential for mutation-based diagnostics to detect endometrial and ovarian cancers earlier.

Their findings were published in the March 21 issue of Science Translational Medicine.

"More than 86,000 U.S. cases of endometrial and ovarian cancer were diagnosed in 2017. Treatment often involves surgery and, in some cases, chemotherapy or radiation," said Amanda Nickles Fader, M.D., director of the Johns Hopkins Kelly Gynecological Oncology Service, Department of Gynecology and Obstetrics, and a corresponding author on this study.

"Additionally for young women who are diagnosed, loss of fertility is common. If we could detect the cancer earlier using a test like PapSEEK, the potential to achieve more cures and preserve fertility in select women could be realized."

Most cancers are curable if they are detected early, and the researchers are exploring ways to use cancer gene discoveries to develop cancer screening tests to improve cancer survival. They announced the development of CancerSEEK, a single blood test that screens for eight cancer types, and UroSEEK, a test that uses urine to detect for bladder and upper tract urothelial cancer.

PapSEEK targets the most common and most lethal gynecological cancers, endometrial and ovarian cancer. There is currently no screening test for endometrial cancer and, due to the obesity epidemic, it is on the rise, particularly in younger women.

"Gynecological cancers are responsible for approximately 25,000 deaths per year and are the third leading cause of cancer-related mortality," said Nickolas Papadopoulos, Ph.D., a senior author and an investigator at the Ludwig Center at Johns Hopkins. "Most of the deaths are caused by tumors that metastasize prior to the onset of symptoms. With PapSEEK, we are aiming to detect these cancers early when they are most curable."

Since fluid from the Pap test occasionally contains cells from the endometrium or ovaries, researchers found they could detect cancer cells from these organs that are present in the fluid.

The researchers studied 1,958 samples obtained from 1,658 women, including 658 endometrial or ovarian cancer patients and 1,002 healthy controls. Some participants provided two samples. Pap brush samples were obtained from 382 endometrial cancer patients and 245 ovarian cancer patients. PapSEEK was nearly 99 percent specific for cancer, and it detected 81 percent of endometrial cancers (78 percent were early-stage cancers) and 33 percent of ovarian cancers (34 percent were early-stage cancers).

Obtaining cervical fluid samples using a Tao brush, which extends further into the cervical canal and collects cells closer to where the cancers could originate, improved the sensitivity of the test. Testing plasma samples with Pap brush samples also increased the test's sensitivity.

Lucy Gilbert, M.D. MSc FRCOG, director of gynecologic oncology at McGill University Health Centre, said, "This allows sampling closer to where the cancers originated. Intrauterine sampling proved particularly important for increasing the detection of ovarian cancer."

Of the 123 endometrial cancer patients studied using Tao brush samples, PapSEEK identified cancer 93 percent of the time. Of the 51 ovarian cancer patients studied, 45 percent tested positive for cancer with PapSEEK. There were no false-positive results.

The Tao brush is not commonly used in the United States but is approved by the U.S. Food and Drug Administration for endometrial sampling. When the plasma and Pap brush samples were both tested, the sensitivity of the test for ovarian cancer increased to 63 percent.

More than 63,000 women are diagnosed with endometrial cancer in the U.S. each year, and more than 11,000 die each year from the disease. Ovarian cancer is less common but more lethal, affecting more than 22,000 women and killing about 14,000 in the U.S. each year.

"Diagnostic tests do not always reliably distinguish benign conditions from cancer, leading to unnecessary procedures," said Nickles Fader. "The high mortality associated with some gynecologic cancers makes screening a priority, and new diagnostic approaches are urgently needed."

"Our study demonstrates the ability to detect endometrial and ovarian cancer using cervical fluids obtained using two different methods," said Yuxuan Wang, first author on the study.