Transvaginal ultrasound has high sensitivity and specificity for detecting endometrial cancer in asymptomatic postmenopausal women, according to a study published online at The Lancet Oncology. Although the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) has yet to determine the role of population screening for endometrial cancer, these findings can be applied currently in women with increased endometrial thickness who undergo a pelvic scan for reasons other than vaginal bleeding.
Researchers evaluated 48,230 women enrolled in the UKCTOCS who underwent transvaginal ultrasound as part of the trial. With a median follow-up of almost 6 years, 136 women had endometrial cancer or atypical endometrial hyperplasia (AEH) within 1 year of transvaginal ultrasound, the primary end point of the study. Researchers separated patients into three risk groups, based on endometrial thickness, to determine the optimal thickness cutoff for transvaginal ultrasound screening.
They found that at the thickness cutoff of 5.15 mm, transvaginal ultrasound had a sensitivity of 80.5% (95% CI, 72.7-86.8) and specificity of 86.2% (95% CI, 85.8-86.6). At 5 mm or greater, sensitivity and specificity were 80.5% (95% CI, 72.7-86.8) and 85.7% (95% CI, 85.4-86.2), respectively; and at 10 mm or greater 54.1% (95% CI, 45.3-62.8) and 97.2% (95% CI,97.0-97.4), respectively.
When the researchers analyzed only the 96 women with endometrial cancer or AEH who reported no symptoms of postmenopausal bleeding before diagnosis and had an endometrial thickness measurement available, sensitivity and specificity at a cutoff of 5 mm decreased (77.1%; 95% CI, 67.8-84.3 and 85.8%; 95% CI, 85.7-85.9). Most of the women who did not have cancer had an endometrial thickness less than 5 mm.
Using logistic regression, the researchers found that 25% of the population is at high risk and that 39.5% of endometrial cancer or AEH cases fell within this group. Based on their analysis, they determined that for this high-risk group the optimum endometrial thickness cutoff is 6.75 mm, which achieved sensitivity of 84.3% (95% CI, 71.4-93.0) and specificity of 89.9% (95% CI, 89.3-90.5).