Abstract
A molecular cervical cancer test based on the Telomerase RNA component (TERC) gene marker is now available as a supplement to Pap screening and HPV co-testing to help doctors evaluate abnormal Pap results.
A molecular cervical cancer test is now available as a supplement to Pap screening and HPV co-testing to help doctors evaluate abnormal Pap results. Quest Diagnostics launched the test, based on the Telomerase RNA component (TERC) gene marker, in late August.
The Pap test for cancerous and precancerous cells in the cervix arguably has been the biggest success story for cancer screening: the American Cancer Society estimates that mortality rates for cervical cancer have dropped by 70% since the advent of widespread Pap testing.
When pathologists performing a Pap screen find abnormal cells classified as low-grade squamous intraepithelial lesions (LSIL), additional testing is strongly recommended. This usually takes the form of HPV testing (if not performed as a co-test), repeat Pap smears every 6 months until normal results are obtained twice in a row, or colposcopy and biopsy. However, only 12% to 16% of women with LSIL will turn out to have a precancerous lesion.
Quest developed a test that can be done on residual cells from a Pap test to help doctors decide which option for management may be best for a patient who has LSILs. The assay uses FISH to detect extra copies of the TERC gene, as well as extra copies of chromosome 3, on which the gene is located. The test is based on NIH research that found that TERC is amplified in precursor cells of cervical cancer and that chromosome 3 can be amplified as well, and was developed under a nonexclusive license from the NIH.
Quest's validation studies have shown that more than 90% of precancerous cells show TERC amplification, whereas fewer than 10% of noncancerous abnormal lesions do, says Daniel Jones, MD, PhD, medical director of the company's cancer diagnostics services in Chantilly, VA. He says that with the longer recommended intervals between Pap tests, doctors want to be sure they know as much as possible about lesions to decide management. The TERC test may allow some women to avoid multiple repeat Pap (or HPV) tests or colposcopy.
Staging for other types of cancers often is much more sophisticated, says Jones. “We want a better understanding of the molecular pathogenesis in cervical cancer.” Quest is now running studies to further validate the TERC test's effectiveness in guiding diagnosis and treatment of cervical dysplasia. Jones says initial data may be published within the year.
