But the discovery of a blood molecule could lead to a test to spot the cancer early.
Researchers at Rush University Medical Center tested for antibodies to mesothelin. That is a substance found on the surface of ovarian cancer cells. They found these antibodies in the blood of those with the disease and in women with infertility who are considered at high risk.
The molecules were not present in healthy women.
Lead researcher Judy Luborsky calls the finding extremely important.
"Now we can define who is at higher risk and find who might in fact benefit from really early treatment, because there are treatments being developed," said Luborsky. "But, again, they are using late stage diseases and many of these treatments are much more effective if given early."
Other experts agree the finding is promising but say more research is needed.
The research is published in the journal Cancer Epidemiology, Biomarkers and Prevention.