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Science Translational Medicine : A Pap Smear for Ovarian Cancer?
Tumor cells shed from ovarian or endometrial cancers are carried into the endocervical canal, where they can be captured by a routine Pap smear for DNA analysis.
[Image courtesy of Elizabeth Cook]
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Analyzing DNA from Pap smears could help detect endometrial and ovarian cancer, according to a new study appearing in the 9 January issue of the journal Science Translational Medicine.
The finding could be a potentially life-saving screening tool for women. The routine Pap smear, which allows doctors to detect abnormal cells in a woman’s cervix, was recently updated to screen for human papillomavirus or HPV using DNA testing.
“This study highlights the promise of ‘precision medicine’ to combat cancer by significantly improving upon the original vision of the Papanicolaou smear test," said Isaac Kinde, a co-author of the study from Johns Hopkins University.
Kinde and colleagues suspected that ovarian and endometrial cancers likely shed a few cells that trickle down into the cervix and possibly could be detected in a Pap smear. The researchers piggybacked on the DNA testing approved for HPV and extended it to look for genetic mutations specific to endometrial and ovarian cancer.
The test identified all of the endometrial cancers in Pap smear samples from women with known endometrial cancer (this cancer is typically diagnosed early on due to the presence of symptoms like vaginal bleeding), but only correctly identified 40% of patients with known ovarian cancer.
However, an early screening option may have the most dramatic impact on women with ovarian cancer, which is often deadly and difficult to diagnose. Importantly, none of the normal samples tested with the new technique showed false positives—that is, none of the healthy women were incorrectly diagnosed with cancer.
"This test can be seamlessly integrated into routine clinical practice,” said Luis Diaz, an associate professor of oncology at Johns Hopkins University and co-author of the study, “and augment the value of the Pap test to screen for ovarian and endometrial cancers in addition to testing for cervical cancer or HPV.”
Although more work is needed to confirm these results in larger groups of patients, the results are promising. Even if the approach cannot identify every ovarian tumor, it may be able to detect more of them earlier and more accurately than existing methods.
"The test needs to be validated on a larger cohort of patients,” Diaz said, “and if confirmed then segue into prospective clinical studies to evaluate the test’s ability to improve survival.”
9 January 2013