An effective screening test for ovarian cancer would rightfully be hailed as a breakthrough. The disease killed 15,000-plus women in the United States last year, in large part because about 70 percent of cases are diagnosed only after the cancer has metastasized elsewhere in the body. So there is great interest in finding possible ways to detect ovarian cancer earlier, when it's much more treatable. Findings from a new and ongoing study of more than 200,000 postmenopausal women suggest that it's feasible to screen that population for the disease using a blood test and ultrasound. However, the results so far leave two major issues unsettled: what the ideal method of screening is and whether finding ovarian cancer early will actually help women live longer.
"This study is incredibly important," says Noah Kauff, director of ovarian cancer screening and prevention at Memorial Sloan-Kettering Cancer Center in New York. "It's assessing whether screening with currently available technology can be useful in reducing the risk of dying from ovarian cancer." We don't yet have that answer; the study's final results aren't expected for another five years or so. Nevertheless, the study has now shown that a screening strategy that uses the CA125 blood test as a first-line test and then follows up suspicious findings with trans-vaginal ultrasound—which uses a tamponlike probe inside the vagina—was able to identify about 90 percent of the women who had cancer (or developed it within the next year). Promisingly, almost half the cancers found were in their early stages.
The study also found that ultrasound by itself can detect 75 percent of cancers, though it leads to more unnecessary surgeries. Another method, untested in this study, is to reverse the combination: first ultrasound, then CA125 to hone the results, says John van Nagell, director of gynecologic oncology at the University of Kentucky Medical Center, who is directing a trial looking at that approach. Details of how these methods should be applied and under what circumstances surgery should be recommended all need to be researched. (To further complicate things, there are new biomarkers under study that may eventually prove better than CA125.)
While the study suggests that either of its experimental methods might pick up ovarian cancer in postmenopausal women, Kauff says, it doesn't tell us how effective they will be for screening purposes. "When the final results of the study are available, that should answer whether we should be offering" some type of screening, he says. And those results should also tell us if early detection of all or some types of ovarian cancer actually saves women's lives, something that is suspected but not nailed down.
It's too soon for women at average risk of ovarian cancer to seek out screening, says Robert Smith, director of cancer screening for the American Cancer Society. (Those at heightened risk because of family history or specific genetic mutations should talk to their doctors about whether and how to screen for the disease.) There's also "a growing appreciation that women with rapid-onset and persistent symptoms might also benefit from this" as a way of ferreting out possible cancer, says Smith.
There's been a push in recent years to make women and their primary-care doctors more aware of the early symptoms of ovarian cancer—namely bloating, pelvic or abdominal pain, difficulty eating or feeling full quickly, and urgent or frequent urination. "If those are new symptoms, occurring almost daily, and last more than two to three weeks, speak to your doctor," says Kauff. "That is still the recommendation for the average woman."