February 13, 2008
WebMD

Ovarian Cancer Blood Test in the Works

Study Shows Test Can Detect Cancer in Early Stages. Yale researchers have developed a simple blood test for ovarian cancer that may do what no current test can -- reliably detect the disease in its early stages while it is still highly curable.

Results from the phase II study showed the test to have an accuracy of nearly 99%.

A phase III trial is under way and should be completed within months, Yale School of Medicine researcher Gil Mor, MD, tells WebMD.

Ovarian cancer is the fifth leading cause of cancer deaths among women in the U.S., even though it is much less common than many other cancers. That is because the disease is most often diagnosed in its late stages when the cancer has already spread beyond the ovaries.

A reliable test for detecting ovarian cancer in its early stages has been an elusive goal, but the Yale researchers believe they may have one.

And an independent review by the National Cancer Institute's Early Detection Research Network (EDRN) confirmed their early findings.

"We now have a test that is significantly better than anything that is available today," Mor says.

Accuracy of Test

The latest research expanded on work the Yale team first published in 2005.

The test has been modified since then and now uses six protein biomarkers instead of four, resulting in an increase in specificity from 95% to 99.4%.

While the difference may not sound like much, from a clinical standpoint it is a big deal.

A test that is 95% specific would result in false-positive readings in 5,000 out of every 100,000 women tested, while a 99.4% specific test would result in a few hundred false-positives.

"A test that is 95% specific may sound good, but that means that one in 20 women who are tested will be told they may have a life-threatening malignancy," American Cancer Society director of cancer screening Robert A. Smith, PhD, tells WebMD. "And these women will have to have a fairly invasive procedure to determine if they have cancer."

The newly published trial, led by Mor, included 362 healthy women and 156 newly diagnosed ovarian cancer patients.

Using a blood test, the researchers looked for evidence of the proteins leptin, prolactin, osteopontin, insulin-like growth factor II, macrophage inhibitory factor, and CA-125.

While each single protein biomarker was not good in differentiating between those with cancer and those without, the combination of the six biomarkers together was found to be highly accurate.

The research appears in the Feb. 15 issue of the journal Clinical Cancer Research.

Finding Ovarian Cancer Early

The test has been licensed to the company Laboratory Corporation of America (Lab Corp) in the U.S., as well as to companies in Israel and China.

It is being offered to high-risk women through Yale's Discovery to Cure program. Mor says roughly 600 women have had it, and several early-stage ovarian cancers have been detected.

Sudhir Srivastava, PhD, led the National Cancer Institute (NCI) team that evaluated and is expanding on the Yale research.

Srivastava tells WebMD that the Yale findings were successfully replicated in an independent lab.

The Yale researchers have now been asked to test stored samples from the huge NCI screening trial that began in 1993.

Some of the samples will be from women who went on to develop ovarian cancer and some will be from women who did not, but the Yale team will not know which samples are which.

If the test can successfully differentiate between the two groups, it may be useful for identifying ovarian cancer in its pre-clinical stages, Srivastava says.

"If this phase of the research succeeds, I would say this is going to be very close to what an ideal [ovarian cancer test] would be," he adds.