Risk of endometrial cancer in asymptomatic postmenopausal women in relation to ultrasonographic endometrial thickness: systematic review and diagnostic test accuracy meta-analysis

OBJECTIVE: This study aimed to evaluate the risk of endometrial carcinoma and atypical endometrial hyperplasia in asymptomatic postmenopausal women concerning the endometrial thickness measured by stratified threshold categories used for performing subsequent endometrial sampling and histologic evaluation. DATA SOURCES: MEDLINE, Scopus, ClinicalTrials.gov, SciELO, Embase, the Cochrane Central Register of Controlled Trials, LILACS, conference proceedings, and international controlled trials registries were searched without temporal, geographic, or language restrictions. STUDY ELIGIBILITY CRITERIA: Studies were selected if they had a crossover design evaluating the risk of atypical endometrial hyperplasia and endometrial carcinoma in postmenopausal asymptomatic women and calculated the diagnostic accuracy of transvaginal ultrasonography thresholds (at least 3.0 mm) confirmed by histopathologic diagnosis. METHODS: This was a systematic review and diagnostic test accuracy meta-analysis according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses of Diagnostic Test Accuracy and Synthesizing Evidence from Diagnostic Accuracy Tests guidelines. Endometrial thickness thresholds were grouped as follows: from 3.0 to 5.9 mm; between 6.0 and 9.9 mm; between 10.0 and 13.9 mm; and 14.0 mm. Quality assessment was performed using the Quality Assessment Tool for Diagnostic Accuracy Studies 2 tool. Publication bias was quantified using the Deek funnel plot test. Coprimary outcomes were the risk of atypical endometrial hyperplasia or endometrial carcinoma according to the endometrial thickness and diagnostic accuracy of each threshold group. RESULTS: A total of 18 studies provided the data of 10,334 women who were all included in the final analysis. Overall, at an endometrial thickness threshold of at least 3.0 mm, the risk of atypical endometrial hyperplasia or endometrial carcinoma was increased 3-fold relative to women below the cutoff (relative risk, 3.77; 95% confidence interval, 2.26e6.32; I 2 ¼74%). Similar degrees of risk were reported for thresholds between 3.0 and 5.9 mm (relative risk, 5.08; 95% confidence interval, 2.26e11.41; I 2 ¼0%), 6.0 and 9.9 mm (relative risk, 4.34; 95% confidence interval, 1.68e11.23; I 2 ¼0%), 10.0 and 13.9 mm (relative risk, 4.11; 95% confidence interval, 1.55e10.87; I 2 ¼86%), and 14.0 mm (relative risk, 2.53; 95% confidence interval, 1.04e6.16; I 2 ¼78%) with no significant difference among subgroups (P¼.885). Regarding diagnostic accuracy, the pooled sensitivity decreased from thresholds below 5.9 mm (relative risk, 0.81; 95% confidence interval, 0.49e0.85) to above 14.0 mm (relative risk, 0.28; 95% confidence interval, 0.18e0.40). Furthermore, the specificity increased from 0.70 (95% confidence interval, 0.61e0.78) for endometrial thickness between 3.0 and 5.9 mm to 0.86 (95% confidence interval, 0.71e0.94) when the endometrial thickness is 14.0 mm. For 3.0 to 5.9 mm and 10.0 to 13.9 mm thresholds, the highest diagnostic odds ratios of 10 (95% confidence interval, 3e41) and 11 (95% confidence interval, 2e49), with areas under the curve of 0.81 (95% confidence interval, 0.77e0.84) and 0.82 (95% confidence interval, 0.79e0.86), respectively, were retrieved. The summary point analysis revealed that the 3.0 to 5.9 mm cutoff point was placed higher in the summary receiver operator curve space than the other subgroups, indicating increased endometrial carcinoma or atypical endometrial hyperplasia diagnosis using these cutoffs. CONCLUSION: Both low and high endometrial thickness thresholds in postmenopausal asymptomatic women seem equally effective in detecting endometrial carcinoma and atypical endometrial hyperplasia. However, although using a 3.0 to 5.9 mm cutoff results in a lower specificity, the offsetting improvement in sensitivity may justify using this cutoff for further endometrial evaluation in patients with suspected endometrial malignancy.