Screening for Ovarian Cancer

By Don Dizon, MD, FACP

"Why can't we screen for ovarian cancer?" It's the one question women want answered, and the one we as women's cancers' specialists are hard-pressed to answer. Ovarian cancer does not present with symptoms until it has advanced beyond the ovary, and even then, the symptoms tend to be fairly non-specific. While CA-125 and pelvic or transvaginal ultrasounds can be used, their utilization as screening tools for ovarian cancer has not been favored as it had never been shown to be very good at picking up early disease and there has not been data to show that their utilization improves survival of women ultimately diagnosed with ovarian cancer.

However, researchers from the United Kingdom are reporting the first results of a screening trial for ovarian cancer in post-menopausal women (www.thelancet.com/journals/lanconc/article/PIIS1470-2045(09)70026-9/abstract). Between the years of 2001 and 2005 this group of investigators enrolled over 200,000 women into this study, which randomized them to no screening versus screening by an annual blood test for the protein CA-125 (which is frequently elevated in advanced ovarian cancer) and by transvaginal ultrasound (combined screening) or by ultrasound alone. Their findings suggested that women were better served by combined modality screening where, compared to ultrasound screening alone, increased compliance was seen (99% versus 95%), decreased frequency of having to repeat a test (8.7% vs. 12%), and less women having to undergo more intensive evaluation (0.3% vs. 3.9%).

Among women undergoing screening, 97 out of the 50,078 women (0.2%) undergoing CA-125 and ultrasound underwent surgery, compared to 845 of the 48,230 (1.8%) women who underwent ultrasound screen alone. Surgery picked up 87 primary cancers with 42 detected among women undergoing combined screening and 45 among those undergoing ultrasound alone. However, the worrisome types of cancers, invasive ovarian cancer, was picked up by combined screening where 33 were invasive, while those undergoing ultrasound had 25 invasive cancers discovered. This means that using ultrasound alone picked up abnormal findings, but they were more likely to be less worrisome types of lesions (such as borderline tumors of the ovary. For more information, try www.cancer.gov/cancertopics/pdq/treatment/ovarian-low-malignant-potential/Patient).

The study lends support to the notion that it may be feasible to screen for ovarian cancer and that combined screening is a more discriminating way to do this, compared to annual ultrasounds alone. Still, what these first results do not show is any impact on survival from ovarian cancer. Therefore, while encouraging, screening on a larger scale cannot be recommended quite yet.