Diagnostic value of the thin-layer, liquid-based Pap test in endometrial cancer: a retrospective study with emphasis on cytomorphologic features

OBJECTIVE: To examine the diagnostic value (sensitivity and specificity of the ThinPrep Pap test in the detection of endometrial cancer and assess the morphologic features of endometrial cancer in ThinPrep tests. STUDY DESIGN: In a retrospective, case-controlled study, we identified 60 Pap slides performed within 12 months of the tissue diagnosis of endometrial carcinoma and 56 comparison slides from patients without known carcinoma. The slides were blindly reviewed by the authors without knowledge of the surgical diagnosis. An independent diagnosis was given for the tests based on 14 diagnostic criteria from the 2001 Bethesda System and 6 additional criteria proposed by the authors. RESULTS: The sensitivity of detecting endometrial carcinoma was 88.3% (95% CI 77.8-94.2%) and specificity was 87.5% (95% CI 76.4-93.8%). The positive likelihood ratio was 7.067 (95% CI 3.513-14.217) and negative likelihood ratio was 0.133 (95% CI 0.066-0.269). Enlarged nuclei and the presence of nucleoli in endometrial cells were the most reliable indicators of endometrial cancer or atypical endometrial cells. CONCLUSION: The ThinPrep Pap test has high sensitivity and specificity in detecting or suggesting the presence of endometrial cancer. Certain cytomorphologic features are helpful in distinguishing benign and malignant endometrial lesions.