Research eyes new ways to spot ovarian cancer
Research eyes new ways to spot ovarian cancer
You're reviewing the medical history for a new patient. The 26-year-old woman complained of back pain for months before a neurologist ordered a magnetic resonance imaging test to check for a herniated disc. The test detected something else: ovarian cancer that has spread to the spine.
While this patient became a cancer survivor, thanks to extensive surgery and chemotherapy, many women are not so lucky. According to the American Cancer Society, ovarian cancer ranks fifth in leading causes of cancer death in women. About 20,180 new cases of ovarian cancer will occur in the United States in 2006, the society estimates. About 15,310 women will die of the disease. Early detection is key: When ovarian cancer presents at a late clinical stage, it is associated with a five-year survival rate of 35%; by contrast, the five-year survival for patients with Stage I ovarian cancer exceeds 90%, and most patients are cured of their disease by surgery alone.1
Ovarian cancer often has few early symptoms and is often diagnosed late, when chances of survival are poor.2 Researchers are looking at several possible diagnostic tools — mainly blood tests and sonograms — to screen for the disease. However, no one test can pick up most early cases without false-positive reports.3
Scientists at the University of Pittsburgh School of Medicine are using a new technology to analyze a large number of proteins, or potential biomarkers, from a very small sample of serum from women with ovarian cancer. They have identified a combination of several biomarkers that could help detect the disease much earlier than it is being diagnosed.
"By the time women are diagnosed, their cancers have already spread and are extremely difficult to treat successfully," says Anna Lokshin, PhD, lead investigator and assistant professor of medicine and pathology at the University of Pittsburgh School of Medicine. "To improve the long-term outcome for women diagnosed with ovarian cancer, we sought to identify a panel of proteins that could signify the presence of early disease," she adds.
The researchers are looking at known proteins at defined concentrations, says Lokshin. By using a new technology called LapMAP, the scientists are able to analyze multiple proteins in a single drop of blood or serum.
By testing 450 serum samples for 46 biomarkers that had previously been correlated with ovarian cancer, Lokshin's research team says it has been able to identify a multi-marker panel, comprised of 20 proteins that correctly recognized more than 98% of serum samples from women with ovarian cancer. The team is performing a case control study to further test its theories, she says.
Repository may help
The National Cancer Institute (NCI) is spearheading a clinical trial that is aimed at building a repository of blood samples in order to develop an accurate means of detecting ovarian cancer soon after the disease returns. By collecting this information, scientists may have a strong lead on how to detect ovarian cancer at an early stage when it can be most effectively treated.
The NCI trial is recruiting patients and, when completed, researchers hope it will give them the needed repository to conduct a detailed proteomic study, says Michael Miller, NCI spokesman. Clinical sites include Fred Hutchinson Cancer Research Center and the University of Washington, both in Seattle; Cedars Sinai Medical Center, Los Angeles; University of Alabama at Birmingham; Duke University Medical Center in Durham; Fox Chase Cancer Center in Philadelphia; University of Texas MD Anderson Cancer Center in Houston; Massachusetts General Hospital in Boston; Northwestern Memorial Hospital in Chicago; Evanston (IL) Northwestern University Hospital; and New York University School of Medicine.
Researchers are looking at several potential screening tests for ovarian cancer; however, none are ready for widespread use. A blood test that measures levels of a protein (CA-125) shed by ovarian cancer cells as well as benign inflamed cells, is used by providers to monitor ovarian cancer patients. Scientists also are eyeing use of transvaginal ultrasound, a sonogram performed with an instrument inserted into the vagina, as a potential screening tool.
More work is needed on use of such techniques in screening for the disease. A 2005 NCI study shows that while transvaginal ultrasound and CA-125 tests, alone or in combination, can detect ovarian cancer, such screening approaches also can produce many false-positive test results.4
While early research on a testing approach known as OvaCheck proved promising, the test has yet to be approved by the Food and Drug Administration (FDA).5 The test uses mass spectroscopy to look for a protein pattern in blood samples that its research group reported as indicative of ovarian cancer.6 However, some scientists have questioned the design and results of the original studies.3 Correlogic Systems in Bethesda, which is developing the test, says it is performing expanded validity tests.7
References
- Ozols RF, Rubin SC, Thomas GM, et al. "Epithelial Ovarian Cancer." In: Hoskins WJ, Perez CA, Young RC, eds. Principles and Practice of Gynecologic oncology. Philadelphia: Lippincott Williams & Wilkins; 2000, pp. 981-1,058.
- Mor G, Visintin I, Lai Y, et al. Serum protein markers for early detection of ovarian cancer. Proc Natl Acad Sci USA 2005; 102:7,677-7,682.
- Rubin R. Ovarian cancer test remains elusive. USA Today; Jan. 29, 2006: Accessed at: www.usatoday.com/news/health/2006-01-29-ovarian-cancer_x.htm.
- Buys SS, Partridge E, Greene MH, et al. Ovarian cancer screening in the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial: Findings from the initial screen of a randomized trial. Am J Obstet Gynecol 2005; 193:1,630-1,639.
- Petricoin EF, Ardekani AM, Hitt BA, et al. Use of proteomic patterns in serum to identify ovarian cancer. Lancet 2002; 359:572-577.
- Wagner L. A test before its time? JNCI 2004; 96:500-501.
- Sullivan MG. FDA raises regulatory issues: Validity testing indefinitely delays OvaCheck release. OB/GYN News 2004; 39:5.
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