A blood test designed for the early detection of ovarian cancer shows real promise if used over time, according to the results of a landmark, 11-year study involving more than 4,000 women.
Researchers at the University of Texas MD Anderson Cancer Center and colleagues made the finding through their use of a test that measures jumps in levels of CA-125, a protein generated in about 80% of ovarian cancers. This new work builds on preliminary data first presented back in 2010, and the journal Cancer published the updated findings.
CA-125 has long been looked at as a potential ovarian cancer biomarker, with mixed success over the years. And Dr. Karen Lu, chair of the Department of Gynecologic Oncology and the study's corresponding author, acknowledges as much. But, she said in a statement, their work established a blood test that screens for CA-125 changes as a potential go-to option for cases of possible early-stage ovarian cancer that's more reliable than initially thought.
"I and other scientists in the gynecologic oncology community thought we would ultimately find a better marker than CA-125 for the early detection of the disease," Lu said. "After looking at new markers and testing them head-to-head in strong, scientific studies, we found no marker better than CA-125."
Researchers enrolled 4,051 healthy, postmenopausal women ages 50-74 at several sites across the country in a prospective, single-arm, 11-year study. The goal: to reach specificity or few false positives. After getting a baseline CA-125 blood test, the researchers grouped the women into "low," "intermediate" and "high" risks groups, based on a mathematical calculation involving a patient's age and CA-125 score. Low-risk patients got retested 12 months later; patients in the intermediate group got a second CA-125 test 90 days later. And those found to be high risk got an immediate referral to a gynecologic oncologist and received a transvaginal ultrasound.
As Time notes in its coverage of the research, CA-125 tests have had mixed results before, in part because they were only used once. This time, their article notes, the repeat testing helped researchers paint a steadier picture of ovarian cancer risks. What they found: Over the 11-year trial, the CA-125 test was 40% accurate in predicting ovarian cancer. But the specificity of the test hit the 99.9% mark. Researchers were happy that the test spotted, in part, four invasive ovarian cancers that were extremely aggressive but treatable and possibly curable because they were caught early. Still, the results are far from definitive, as the researchers note, and the accuracy level thus far is not extraordinarily high. Another trial is planned, however, that will test the CA-125 blood test and three others to see what cancers could be missed with just the CA-125 diagnostic on its own.
In other words, more research is necessary to establish anything game-changing here. But as Lu herself notes, the results appear to be a promising first step. The research team cites American Cancer Society statistics that conclude more than 22,000 women will be diagnosed with ovarian cancer in 2013, with many identified at the life-threatening, advanced stage. And of that number 14,000-plus will die from the disease. Having a way to diagnose ovarian cancer sooner can boost a patient's survival chances, and so the MD Anderson CA-125 work could move the field one step closer to that goal.