A DNA analysis of cervical cells taken from routine smear tests could identify people who might benefit from additional screening for ovarian cancer
1 February 2022
Molecular clues collected from routine cervical swabs can be used to identify people who have ovarian cancer. In future, these epigenetic patterns could help doctors predict which individuals are at high risk of developing the disease, so they can be screened with more sensitive methods to catch tumours early.
Currently, 75 per cent of ovarian cancers are picked up at a late stage when the tumour has spread throughout the abdomen and survival rates are low.
Martin Widschwendter at the University of Innsbruck in Austria and his colleagues have developed a new test that can correctly identify more than 70 per cent of people under 50 with ovarian cancer at a range of disease stages, and 55 per cent of people over 50.
The method involves looking at cells from the cervix. In many countries, people are already offered regular smear tests, in which a small sample of cells is taken from the cervix, to search for signs that indicate a high risk of cervical cancer.
To assess the likelihood of ovarian cancer, the new test looks for small molecules called methyl groups that are tagged onto certain sequences of DNA, creating epigenetic marks.
“Epigenetic marks record the environmental factors that the individual has experienced. This includes events during embryonic development, but also lifestyle factors like smoking, and hormonal changes,” says Widschwendter. “In this way, the test provides a simple and easy-to-access method to assess many risk factors that contribute to ovarian cancer risk.”
The researchers used machine learning to analyse DNA samples from cervical swabs of an initial group of 242 people with cancer and 869 healthy people. This allowed them to identify a unique signature of epigenetic marks found in DNA from people with ovarian cancer but not healthy people. They then validated their approach in a second data set collected from 47 people with cancer and 227 healthy samples.
Next, Widschwendter and his team aim to show that this test can predict people’s risk of developing ovarian cancer in the future. The idea is that if the test shows that someone has a high risk of ovarian cancer, they can then be screened more frequently using sensitive blood tests for the presence of cancer, says Widschwendter. If those blood tests are positive and cancer is confirmed, they can undergo surgery to remove the tumour.
However, all cancer screening tests sometimes flag cancers incorrectly, which may result in people undergoing unnecessary treatment. The team’s test misidentified healthy people as having ovarian cancer 25 per cent of the time.
“We will need to develop ways to communicate the results of the test and make sure people understand what it means,” says Widschwendter.
Journal reference: Nature Communications , DOI: 10.1038/s41467-021-26615-y
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