October 3, 2008
Ovarian-Cancer Test Hasn’t Matched Hype
By ROSALIE ROBLES CROWE
September is National Ovarian Cancer Awareness Month, and this year it appeared that a new screening test would translate to major inroads against the disease.In June, OvaSure, an ovarian cancer screening test went on the market, touted by its manufacturer, LabCorp, for its high accuracy in predicting which women in a high-risk group would get ovarian cancer.
The company claimed "high specificity" - 99.4 percent - in its ability to discriminate between disease-free women and those with stage IV ovarian cancer.
But that's a stretch, says Dr. David Alberts, director of the Arizona Cancer Center and a specialist in ovarian cancer. He urged caution before using OvaSure.
The testing was done on small sets of women known to be free of cancer and also on women who had various stages of ovarian cancer. The initial publication of the results erroneously showed a greater than 99 percent positive predictive value. Later, that data were retracted and changed to a 6.5 percent positive predicted value.
Their testing statistics show that one of 15 women (6.5 percent) with positive test results actually will have ovarian cancer.
But since the testing would be aimed at women with average-to- high risk for the disease, the other 14 who test positive will be faced with the pressure of having to decide whether to go on with further testing or even surgery to remove their ovaries, Alberts said.
"The point simply is that the test has not been studied adequately in either the average-risk or in the high-risk (55-75) age group," he said.
John R. van Nagell, director of gynecologic oncology at the University of Kentucky Chandler Medical Center, speaking to McClatchy Newspapers, echoed Alberts' criticism.
"What women need to realize," he said, "is that the test doesn't diagnose anything. This predicts whether in the presence of ovarian tumors there is a risk of malignancy. What if it's wrong?"
Alberts is chairman of the Cancer Prevention Group of the Gynecologic Oncology Group, an international research group focused on women's cancers. It is the largest such group in the world. That group is preparing to evaluate OvaSure to see if it can determine who will and who will not have a recurrence of the disease.
Currently, 55 percent of ovarian cancer patients go into remission, but the cancer recurs in 75 percent of them, Alberts said.
Alberts had been conferring with the developers of the test, helping them find populations to test.
"It really shocked me," he said, when LabCorp began advertising OvaSure as a test boasting a 99 percent accuracy rate in predicting early-stage ovarian cancer.
LabCorp released OvaSure to the marketplace without U.S. Food and Drug Administration validation.
FDA approval is not required because OvaSure is a blood test done in a centrally located laboratory.
Nevertheless, in August, the FDA labeled the marketing of the individual tests as a potential public health risk.
Ovarian cancer is the deadliest of all gynecological cancers and the fourth-leading cause of cancer deaths in American women.
* Includes information from Amy Wilson of McClatchy Newspapers.
Originally published by ROSALIE ROBLES CROWE, ARIZONA DAILY STAR.
(c) 2008 Arizona Daily Star. Provided by ProQuest LLC. All rights Reserved.