Transvaginal Ultrasound Detects Endometrial Cancer Before Symptoms Arise

Transvaginal ultrasound screening (TVS) has good (80% - 90%) sensitivity and specificity at detecting endometrial cancer before symptoms appear in postmenopausal women, according to the first large-scale study to evaluate the performance of TVS screening for endometrial cancer. However, the findings revealed that additional research to assess acceptability, health economics, and risk are needed before routine population screening or targeted screening for endometrial cancer can be advocated.

The study's findings were published online December 2010 in the journal the Lancet Oncology. Endometrial cancer is the most common gynecologic cancer. However, because of the good prognosis of patients with endometrial cancer compared with other cancers, few studies have been done to assess the benefits of screening in asymptomatic women. However, increasing obesity, falling fertility, and an aging population suggest that incidence will continue to rise.

Up to now, no screening test to detect early stage endometrial cancer in asymptomatic women has been shown to be effective. Measuring endometrial thickness with TVS has been suggested as a potential screening method.

To investigate the performance of TVS screening on a large scale, a team led by Ian Jacobs from the University College London (UK), analyzed data from the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS). As part of the trial, TVS was performed on 37,038 postmenopausal women. The researchers calculated the performance characteristics of endometrial thickness (ET) and endometrial abnormalities at detecting endometrial cancer within one year of TVS screening, and examined the sensitivity and specificity of TVS for different risk groups. Modeling using epidemiologic variables was performed to assess a screening strategy for women at higher risk.

In the 133 women diagnosed with endometrial cancer or atypical endometrial hyperplasia (AEH) within one year of screening, 107 (81%) had an ET of 5 mm or greater. Most of the 36,731 women who did not have cancer had an ET of less than 5 mm. At the optimum ET cutoff of 5.15 mm, TVS would detect 80.5% of cancer cases (sensitivity) and would have a 14.3% false-positive rate (85.7% specificity). Using this threshold, if the entire population was screened, one case of endometrial cancer would be detected for every 47.7 women.

The authors pointed out that although the number of false-positives could be reduced considerably by increasing the cutoff for ET, this would result in a corresponding fall in sensitivity. An increased cutoff of 10 mm would identify 54.1% of cancer cases with 97.2% specificity, and 17 women would undergo further procedures to detect each case of endometrial cancer.

When the analysis was restricted to the 96 women with cancer who reported no symptoms of postmenopausal bleeding at the scan, an ET cutoff of 5 mm was able to detect 77.1% of women who developed cancer with a 14.2% false-positive rate.

Moreover, the modeling analysis detected 25% of the population as at high risk, and this high-risk group included 40% of endometrial cancer or AEH cases. In this group, the optimum ET cutoff of 6.75 mm would detect 84.3% of cancer cases and achieve a specificity of 89.9%. According to the researchers, "this would reduce the burden of screening to 25% of the population with detection of about 40% of the cases.”

The researchers reported, "A targeted screening approach might help reduce the overall number of false-positive findings while maintaining a high sensitivity.” They concluded, "Although the role of population screening for endometrial cancer remains uncertain, the findings are of immediate value in the management of increased endometrial thickness in postmenopausal women undergoing pelvic scans for reasons other than vaginal bleeding...Our findings provide the basis for further studies to assess the acceptability, health economics, and risk stratification.”

In a comment in the same issue, Dr. Ignace Vergote and colleagues from University Hospitals Leuven (Leuven, Belgium) cautioned that the findings do not prove "a benefit for screening for endometrial cancer because of an absence of survival data. The study...provides important ultrasonographic endometrial findings in asymptomatic postmenopausal women, but screening for endometrial cancer with ultrasonography has not been sufficiently proven to be beneficial because of the high cost, the prevalence of cancers that are not clinically relevant or hyperplasia, the number of unnecessary surgical interventions and associated morbidity, the presence of clinically detected symptoms such as bleeding that happen at an early stage in many women with endometrial cancer, and the absence of prospective randomized trial data that show a survival benefit in screened patients.”

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