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‘PapGene’ Test Detects Ovarian, Endometrial Cancers
Using cervical fluid obtained during routine Pap tests, scientists at the Johns Hopkins Kimmel Cancer Center have developed a test to detect ovarian and endometrial cancers. In a pilot study, the “PapGene” test — which relies on genomic sequencing of cancer-specific mutations — accurately detected all 24 (100%) endometrial cancers and nine of 22 (41%) ovarian cancers. The new findings were published in Science Translational Medicine.
The investigators noted that larger-scale studies are needed before the test can be clinically implemented, but they believe the new method has the potential to pioneer genomic-based cancer screening tests. The Papanicolaou (Pap) test — during which cells collected from the cervix are examined for microscopic signs of cancer — is widely and successfully used to screen for cervical cancers. However, no routine screening method is available for ovarian or endometrial cancers.
Since the Pap test occasionally contains cells shed from the ovaries or endometrium, cancer cells arising from these organs could be present in the fluid as well, said Luis Diaz, MD. “Our genomic sequencing approach may offer the potential to detect these cancer cells in a scalable and cost-effective way,” he adds.
Cervical fluid of patients with gynecologic cancer carries normal cellular DNA mixed with DNA from cancer cells, according to the investigators. Their task was to use genomic sequencing to distinguish cancerous from normal DNA.
Using ovarian and endometrial cancer genome data, the researchers identified 12 of the most frequently mutated genes in both cancers and developed the PapGene test with this insight in mind.
The investigators then applied the PapGene method to Pap test samples from ovarian and endometrial cancer patients. The new test detected both early and late-stage disease in the endometrial and ovarian cancers tested. No healthy women in the control group were misclassified as having cancer.
Next, the investigators plan to apply the PapGene test to more samples and to work to increase the test’s sensitivity in detecting ovarian cancer. “Performing the test at different times during the menstrual cycle, inserting the cervical brush deeper into the cervical canal, and assessing more regions of the genome may boost the sensitivity,” said Chetan Bettegowda, MD, PhD.
Together, ovarian and endometrial cancers are diagnosed in nearly 70,000 women in the U.S. each year, and about one-third of these women will die from the disease.
“Genomic-based tests could help detect ovarian and endometrial cancers early enough to cure more of them,” said graduate student Yuxuan Wang, who notes that the cost of the test may be similar to that of current cervical-fluid testing for human papillomavirus (HPV), which is less than $100.
Source: Johns Hopkins School of Medicine; January 9, 2013.