A new gene-based screening test that could lead to earlier detection of ovarian and endometrial cancers

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Pushing screening of ovarian and endometrial cancers one step further Credit: McGill University
Pushing screening of ovarian and endometrial cancers one step further Credit: McGill University

Ovarian and uterine cancers, when detected early, has a higher chance of being cured. However, in most of the cases, it is diagnosed at a later stage causing a lot of suffering and mortality among women.

Keeping this in mind, a team of researchers from the Research Institute of McGill University Health Centre (RI-MUHC) and Johns Hopkins have developed a test that could provide a safe and minimally invasive method for diagnosing ovarian and endometrial cancers earlier and are one step closer to clinical implementation.

The test coined PapSEEK, aims to analyze small amounts of cancer DNA obtained from Pap samples from the cervix, uterus as well as blood, and identify common genetic mutations associated with these cancers.

It all began when Dr. Lucy Gilbert at the MUHC, who had prior expertise in gynecological cancers, proposed to the team at Johns Hopkins to collect samples not just from the cervix but also from inside the uterus, to increase the likelihood of detection of cancers from the ovaries, fallopian tubes and uterus while the cancer is still in its early stages.

Dr. Lucy Gilbert’s team guided the team at Johns Hopkins on the Tao brush technique ─ a technique that extends the brush into the uterus allowing for the collection of cells closer to where the cancers could originate, thus improving the sensitivity of the test. The pap smear relies on the cancer cells reaching the cervix.

Pushing screening of ovarian and endometrial cancers one step further Credit: McGill University
Pushing screening of ovarian and endometrial cancers one step further Credit: McGill University

Soon, the research team found that samples taken from the uterus were more likely to detect ovarian and uterine cancers than that of the cervix.

PapSEEK: safer and less invasive for patients

Researchers tested the effectiveness of PapSEEK on samples gathered from 382 patients with endometrial cancer, 245 patients with ovarian cancer and 714 healthy controls from different hospital sites across the U.S., Denmark, Sweden and Canada.

Using PapSEEK, researchers were able to detect 81 percent of endometrial cancers (78 percent were early stage cancer) and 33 percent of ovarian cancers (34 percent were early-stage cancers). More interestingly, these rates rose to 93 percent and 45 percent (respectively) when samples were gathered with the Tao brush technique. There were no false-positive results.

Endometrial and ovarian cancers together are the third most common cause of cancer deaths in women in North America and other high-income countries. Existing tests such as transvaginal ultrasound rely on nonspecific factors such as size of the tumor and may be positive only after the more aggressive forms have spread to other organs. Imaging also results in many false positives, highlighting the need for a more reliable screening tool.

“In high grade ovarian and uterine cancers, cells detach easily and spread while the tumors are still small and not noticeable,” adds Dr. Gilbert. “Currently, there are no tests available to allow diagnosis of these aggressive subtypes of cancer in earlier stages, because they have not caused symptoms and are not easily identified by medical examinations.”

In this study, researchers took advantage of the fact that tumor cells from ovarian or endometrial cancers are often carried into the endocervical canal, where they can be gathered with a Pap brush.

“This special brush sampling procedure is a simple outpatient technique, which any trained gynecologists can carry out in a clinic without anesthesia,” explains Dr. Kris Jardon, study co-author, who is a gynecologic oncologist at the McGill University Health Centre and a scientist from the Cancer Research Program at the RI-MUHC. “This increases the likelihood of widespread clinical implementation after we have carried out the appropriate validation steps”

“The cervical routine Pap test has dramatically decreased the deaths from cervical cancer,” says Dr. Gilbert, “but it is unable to detect endometrial or ovarian cancers, the most lethal and most common gynecologic malignant tumors in countries where Pap tests are routinely performed. We have shown this special uterine Pap test has the potential to be developed into an outpatient screening test that can do for uterine and ovarian cancers what the cervical pap test did for cervical cancer.”

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

Source: McGill University