MONDAY, May 9, 2005 (HealthDay News) -- Yale researchers have developed a blood test they hope will be able to detect ovarian cancer while it is still in its early stages.
In preliminary experiments, the test -- for four different proteins -- distinguished between healthy women and women with ovarian cancer with 95 percent effectiveness.
Experts cautioned, however, against too much optimism.
"This is not the answer," said Dr. David Fishman, director of gynecologic oncology, cancer prevention and early detection at New York University Cancer Institute, and director of the National Ovarian Cancer Early Detection Program. "These proteins are not unique to ovarian cancer. Further evaluation is required to see if this has any clinical relevance."
But it could be a hopeful note. "It's basically making us optimistic that we will attain the testing that we need," added Dr. Robert Morgan Jr., section head of medical gynecologic oncology at City of Hope Cancer Center in Duarte, Calif.
Fishman and Morgan were not involved in the new study.
Ovarian cancer is particularly sinister because it seldom has symptoms in the early stages. It is the leading cause of gynecologic cancer deaths in the United States, and although it is one-tenth as common as breast cancer, it is three times more deadly. When caught in its early stages, however, about 70 percent to 80 percent of ovarian cancers can be cured.
Researchers have long been looking for an effective screening method to catch the disease earlier, when it is more likely to be cured with treatment.
"We really, seriously need a good screening test for ovarian cancer because if patients are diagnosed with stage I cancer, they have at least a 90 percent chance of being cured," Morgan said. "The problem is that 70 to 80 percent are diagnosed already in stage III or IV, and the best we can do with that group is to cure only about 15 to 20 percent."
This is not the first time experts have found markers, but none of them have panned out. "While promising, we have not been as successful as we would like with these tests," Morgan said.
The authors of the study, which appears in the May 10 issue of the Proceedings of the National Academy of Sciences, first determined blood levels of 169 proteins in 28 healthy women, 18 women recently diagnosed with ovarian cancer and 40 women with long-standing disease.
Four proteins turned out to show significantly different levels in healthy women versus women with malignancies.
The researchers then developed a blood test for ovarian cancer based on the four proteins: leptin, prolactin, osteopontin and insulin-like growth factor-II.
Tests of more than 200 women showed that if the levels of two or more of these biomarkers fell within a certain range, a tumor was present. The test was 95 percent effective in identifying ovarian cancer, including stage I and stage II malignancies.
For reasons that were not entirely clear, none of the proteins on their own could single out cancer patients.
The test could be used on an investigative basis to test women who are at high risk for breast and/or ovarian cancer, said study co-author Patricia Bray-Ward, a senior research scientist at the Nevada Cancer Institute in Las Vegas. Other tests would have to be performed to determine what kind of tumor was present. "If someone tested positive on this test, I wouldn't assume they had ovarian cancer," Bray-Ward said.
"The test is not good enough for general screening," added David Ward, deputy director of the Nevada Cancer Institute and senior author of the study. "We have identified several other markers which we need to incorporate into ongoing studies. We need to get to 99 percent-plus effectiveness to be able to do a general screen."
The overall incidence of ovarian cancer is sufficiently low that a test would have to be extremely specific to not generate large numbers of false positives, Morgan explained.
Ward is also hoping the markers may one day contribute to the development of a general cancer screening test. "The blood test would say you've got cancer," he said. "A second test would say what kind. This is not something we have now. This is something we'd love to have."
More information
For more on ovarian cancer, visit the National Ovarian Cancer Coalition.
