Adequacy rate comparison between liquid-based cytology using SurePath versus conventional smears in detecting thyroid malignancies

Background: Controversy exists about the diagnostic value of liquid-based cytology (LBC) compared to conventional smears (CS). Most prior studies of LBC were performed using ThinPrep system. Few studies have ever compared the adequacy rate of SurePath with conventional smears. Methods: We performed a prospective comparison of LBC using SurePath with CS in 304 thyroid nodules. Four needle sticks constituted a single nodule FNA, with 2 passes used for CS while the other 2 passes were used for SurePath. Cytopathologists separately read all samples, and all slides were reported using the Bethesda system for reporting thyroid cytology. The adequacy rate was compared between the CS and SurePath groups. Results: The adequacy rate for all solid nodules was 78.2% in CS group, significantly higher than 68.0% in the SurePath group (P=0.006). No significant difference was seen for mixed or cystic nodules. The adequacy rate using a combination of CS and SurePath in solid nodules was 86.4%, significantly higher than 78.2% in CS group (P<0.001). When excluding nodules less than 1 cm, the adequacy rate of CS for solid nodules was 83.5%, significantly higher than 71.3% in SurePath group (P=0.02). The adequacy rate of combination of CS and SurePath was 91.3% for solid nodules, significantly higher than 83.5% in CS group (P=0.04). Conclusion: Our study showed that LBC using SurePath is not superior to conventional smears. However, a combination of both SurePath and CS may yield the most favorable adequacy rate compared to either process separately.