Researchers have taken a small but potentially significant step toward early detection of ovarian cancer, a deadly disease often diagnosed too late for effective treatment.
Various cancer “biomarkers” show up in blood tests long before symptoms occur but aren’t accurately predictive until later, when tumors probably have reached an advanced stage, scientists at the Fred Hutchinson Cancer Research Center in Seattle found.
The study, published today in the Journal of the National Cancer Institute, was headed by Garnet Anderson and Nicole Urban of the Hutchinson center’s Division of Public Health Sciences.
“What this study did was move one step closer to early detection,” said Anderson, a biostatistician. “It gives us an idea of where we want to go, but doesn’t solve the problem.”
For several years, the ovarian cancer researchers have focused on biomarkers, proteins secreted by tumors, hoping to find one or more that show up early in the disease’s progress. Few ovarian cancer cases are diagnosed early, when treatment has a high cure rate.
The researchers analyzed stored blood samples collected over several years for a previous research study involving female smokers. Ultimately, 34 of those women were diagnosed with ovarian cancer. Looking at the blood samples, taken periodically up to 18 years before diagnosis, the researchers found that three of six biomarkers, including one known as CA125, increased in cancer patients up to three years before diagnosis, compared with patients without ovarian cancer.
But at that early stage, the levels weren’t high enough to accurately predict the disease, researchers found. A high degree of accuracy is required for such tests, the researchers wrote, “because a definitive diagnosis requires surgery.”
Only at a year or less before the women were diagnosed did the biomarkers’ levels in the blood become more accurate.
A cancer expert who was not involved in the study said any lead time could help.
“Finding ovarian cancer a year earlier could have a significant impact,” said Dr. Barbara Goff, a surgeon and director of gynecologic oncology at the University of Washington. “Even three months makes a huge difference when you’re going into someone’s belly.”
Goff said results may have been skewed because samples came from smokers. “It’s unclear whether that could have altered the biologic nature of these biomarkers.”
Even so, she termed the study’s results “incredibly exciting -- but very, very preliminary.”
In the U.S., more than 21,000 women were diagnosed with ovarian cancer last year, and nearly 15,000 died from it, according to the American Cancer Society. A woman’s risk of getting invasive ovarian cancer increases with age; overall, a woman has a 1 in 71 chance of contracting the disease. Early symptoms, such as bloating and abdominal pain, can be mistaken for common ailments.
Researcher Urban is an ovarian cancer survivor. She was diagnosed nearly 40 years ago virtually by accident, while she was being treated for another ovarian condition.