Task Force Says No to Routine Screening for Ovarian Cancer

Elizabeth DeVita-Raeburn

September 10, 2012

September 10, 2012 — The US Preventive Services Task Force has recommended against routine preventive screening of asymptomatic women with no risk factors for ovarian cancer in a report published online September 10 in the Annals of Internal Medicine.

The report echoes a recommendation made by the task force in 2004, which found that "the potential harms outweighed the potential benefits of screening." However, this new recommendation factors in additional literature reviews commissioned by the task force in 2008 and 2011. The reviews found no new evidence that routine screening reduced mortality in women with no symptoms or risk factors, but concluded that it could cause significant harm to patients in the form of unnecessary surgical procedures resulting from false-positive results.

Screening for ovarian cancer usually consists of cancer antigen (CA)-125 serum testing alone or in conjunction with transvaginal ultrasonography. "The evaluation of abnormal test results consists of either repeat testing or, frequently, removal of one or both of the ovaries via laparoscopy or laparotomy," according to the report.

Ovarian cancer is the fifth leading cause of cancer deaths in women and is the most lethal of all gynecological cancers, according to the report. However, the disease is rare, with an age-adjusted incidence of 13 cases per 100,000.

That means that "the positive predictive value of screening for ovarian cancer — which directly depends upon the prevalence of the disease — is low, and the majority of women with a positive screening test will have a false-positive result," the authors write.

Evidence-Based Recommendation

The report cites evidence from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, a single, randomized, controlled study in which 78,216 women in the United States were randomly assigned to either usual care or 6 years of serum CA-125 testing and 4 years of transvaginal ultrasonography, and were followed up for 13 years. Abnormal tests results were managed by the women's personal physicians.

"Although there was a nonstatistically significant finding of an increased number of ovarian cancer cases diagnosed in the screening arm compared with controls (212 vs. 176 cases; relative risk [RR], 1.21 [95% (confidence interval [CI]), 0.99-1.48], no difference was found in either stage at diagnosis or death rate from ovarian cancer (118 vs. 100 deaths; RR, 1.18 [95% CI, 0.82-1.71]," the authors write.

In the same trial, however, 10% of women in the screening group received a false-positive result at some point during the study, and one third of these women had an oophorectomy. The positive predictive value of CA-125 testing and transvaginal ultrasound, the authors write, was just more than 1%. The ratio of surgeries to ovarian cancers detected via screening was approximately 20 to 1. Furthermore, "there were nearly 21 major complications per 100 surgical procedures performed on the basis of false-positive screening results."

The authors of the report also cite a randomized trial within the Shizuoka Cohort Study of Ovarian Cancer, which used transabdominal or transvaginal ultrasonography and serum CA-125 testing concurrently. This trial "reported that an estimated 33 surgeries were required to diagnose 1 case of screen-detected ovarian cancer."

The UK Collaborative Trial of Ovarian Cancer Screening, an ongoing randomized trial, is attempting a more nuanced approach to screening: annual serum CA-125 testing, with ultrasonography as follow-up for abnormal results. The investigators are also employing an algorithm when interpreting CA-125 serum results that takes into account age, absolute CA-125 levels, and CA-125 trajectory over time compared with annual screening with transvaginal ultrasonography or no screening, the report's authors explain.

Preliminary data from the pilot study found that 20% of women in the multimodality group who were first categorized as intermediate risk required up to 5 follow-up blood tests before being reclassified as low risk. "Less than 1% of participants had surgery to investigate an abnormal screening result," the authors write, "however, of the 16 women that did have surgery, 11 (69%) did not have ovarian cancer."

The final results of the UK trial "should provide more information about the relative benefits and harms of an algorithm-based approach to screening for ovarian cancer," the authors conclude.

The task force's current recommendation with regard to preventive screening for ovarian cancer in asymptomatic women with no risk factors concurs with recommendations issued by both the American Congress of Obstetricians and Gynecologists and the American Cancer Society.

The authors have disclosed no relevant financial relationships.

Ann Intern Med. Published online September 10, 2012. Full text

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