Clinical study on primary screening of oral cancer and precancerous lesions by oral cytology

Background: This study was conducted to compare the histological diagnostic accuracy of conventional oral-based cytology and liquid-based cytology (LBC) methods. Methods: Histological diagnoses of 251 cases were classified as negative (no malignancy lesion, inflammation, or mild/moderate dysplasia) and positive [severe dysplasia/carcinoma in situ (CIS) and squamous cell carcinoma (SCC)]. Cytological diagnoses were classified as negative for intraepithelial lesion or malignancy (NILM), oral low-grade squamous intraepithelial lesion (OLSIL), oral high-grade squamous intraepithelial lesion (OHSIL), or SCC. Cytological diagnostic results were compared with histology results. Results: Of NILM cytology cases, the most frequent case was negative [LBC n = 50 (90.9%), conventional n = 22 (95.7%)]. Among OLSIL cytodiagnoses, the most common was negative (LBC n = 34; 75.6%, conventional n = 14; 70.0%). Among OHSIL cytodiagnoses (LBC n = 51, conventional n = 23), SCC was the most frequent (LBC n = 31; 60.8%, conventional n = 7; 30.4%). Negative cases were common (LBC n = 13; 25.5%, conventional n = 14; 60.9%). Among SCC cytodiagnoses SCC was the most common (LBC n = 16; 88.9%, conventional n = 14; 87.5%). Regarding the diagnostic results of cytology, assuming OHSIL and SCC as cytologically positive, the LBC method/conventional method showed a sensitivity of 79.4%/76.7%, specificity of 85.1%/69.2%, false-positive rate of 14.9%/30.7%, and false-negative rate of 20.6%/23.3%. Conclusions: LBC method was superior to conventional cytodiagnosis methods. It was especially superior for OLSIL and OHSIL. Because of the false-positive and false-negative cytodiagnoses, it is necessary to make a comprehensive diagnosis considering the clinical findings.