A simple smear test for cervical cancer can now pick up ovarian and endometrial cancers before they turn deadly.
Ovarian and endometrial cancers are the fifth and sixth leading causes of cancer deaths in women. They are difficult to treat because they often spread to other parts of the body before symptoms arise.
A smear test, also known as a Pap test, uses a brush to collect cells from the cervix. These are studied under the microscope to look for cancerous changes or tested for the presence of human papillomavirus, 鈥媤hich can sometimes lead to cervical cancer.
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Lucy Gilbert at McGill University Health Centre in Montreal, Canada, and her colleagues wondered if the Pap test could be adapted to other cancers of the female reproductive tract.
Gilbert鈥檚 team found that the Pap brush also picks up cancer cells that have shed from the ovaries and endometrium and pooled at the cervix. They identified these cells by looking for cancer-related mutations in 18 key genes.
This genetic approach was able to detect 33 per cent of ovarian cancers and 81 per cent of endometrial cancers in Pap test specimens collected from 627 women already diagnosed with these diseases.
To improve the accuracy of the test, the researchers used a Tao brush that reaches beyond the cervix to collect cells closer to the ovaries and endometrium. They also looked for cancer DNA markers in the women鈥檚 blood.
The detection rate for endometrial cancer improved to 93 per cent using the Tao brush. It rose to 63 per cent for ovarian cancer using the combined blood test. In both approaches, over half the cases detected were early cancers.
This is promising because the cure rate for early-stage ovarian and endometrial cancers is over 70 per cent, compared with 15 per cent for later stages.
Importantly, no positive test results came back for over 300 women without cancer who were also part of the study, which is vital for preventing unnecessary anxiety and interventions.
The researchers are now planning a larger trial in women over the age of 50, who are most at risk of developing these cancers. If the test is approved, women could be screened for cervical, ovarian and endometrial cancer in one go during their routine Pap test, says Gilbert. 鈥淲e think it will be a game changer.鈥�
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Science Translational Medicine
