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New Screening Strategy May Catch Ovarian Cancer at Early Stages
A new screening strategy for ovarian cancer appears to be highly specific for detecting the disease before it becomes lethal. The strategy is described in a study published online in Cancer, a journal of the American Cancer Society. If the new strategy can be verified in an ongoing clinical trial, it could potentially help save the lives of thousands of women each year in the U.S., the authors say.
There are no established screening strategies for ovarian cancer. The disease often causes no specific symptoms and is difficult to detect in the early stages, when it is most responsive to treatment. Therefore, ovarian cancer is highly lethal because most women have advanced disease at diagnosis.
Karen Lu, MD, of the University of Texas MD Anderson Cancer Center in Houston, led a team that tested the potential of a two-stage ovarian cancer screening strategy that incorporates changes in a blood protein called CA125, which is a known tumor marker. In their 11-year study, 4,051 postmenopausal women initially underwent an annual CA125 blood test. Based on a calculation called the Risk of Ovarian Cancer Algorithm, women were divided into three groups: those who should receive another CA125 test 1 year later (low risk); those who should receive a repeat CA125 in 3 months (intermediate risk); and those who should receive a transvaginal ultrasound and be referred to a gynecologic oncologist (high risk).
An average of 5.8% of women were found to have an intermediate risk each year, meaning that they should receive a CA125 test in 3 months. The average annual referral rate to transvaginal ultrasound and review by a gynecologic oncologist was 0.9%. Ten women underwent surgery based on their ultrasound exams. Four had invasive ovarian cancers; two had ovarian tumors of low malignant potential; one had endometrial cancer; and three had benign ovarian tumors. This equates to a positive predictive value of 40% for detecting invasive ovarian cancer. The specificity of the testing strategy was 99.9%, meaning that only 0.1% of patients without cancer would be falsely identified as having the disease. Importantly, all of the ovarian cancers were at an early stage.
“The results from our study are not practice-changing at this time; however, our findings suggest that using a longitudinal (or change-over-time) screening strategy may be beneficial in postmenopausal women with an average risk of developing ovarian cancer,” Lu said.
Source: Wiley; August 26, 2013.