Min Woo Lee1, Sang Hyub Lee1, Jung Won Chun1, Gunn Huh1, Nam Young Park1, Joo Seong Kim1, In Rae Cho1, Woo Hyun Paik1, Ji Kon Ryu1, Yong Tae Kim1, Hae Ryoung Kim2, Kyoung Bun Lee2

1Department of Internal Medicine-GI/Hepatology, Seoul National University Hospital, Seoul, Korea, 2Department of Pathology, Seoul National University Hospital, Seoul, Korea.

Corresponding Author
Sang Hyub Lee, Seoul National University Hospital, Department of Internal Medicine and Liver Research institute, Jongno-gu, Korea (the Republic of), gidoctor@snuh.org

Background/Aims: Brush cytology under endoscopic retrograde cholangiopancreatography (ERCP) is the primary diagnostic test for biliary tract cancer. However, it suffers from low sensitivity. SurePath liquid-based cytology (LBC) was shown to improve the diagnostic efficacy of brush cytology for thyroid, cervical, and pancreatic cancer. To evaluate the diagnostic performance of SurePath LBC for biliary tract cancer, we compared it with conventional smears and forceps biopsies.

Methods: A retrospective comparative study was conducted of all consecutive patients who underwent brush cytology under ERCP from January 2010 to April 2020. The primary outcome was the diagnostic efficacy of conventional smears and SurePath LBC. The difference between the two groups was corrected using inverse probability weighting (IPW). The secondary outcome was the sensitivity and specificity of brush cytology and forceps biopsy. The secondary outcome was evaluated in patients who underwent both methods.

Results: Among 156 patients, conventional smears were performed in 76 patients and SurePath LBC was performed in 80 patients. In the primary outcome analysis using IPW, the sensitivity of conventional smears and SurePath LBC was 58.88% and 80.95% respectively (p = 0.0002). The specificity was 100% for both methods. The accuracy was 69.86% for conventional smears and 84.42% for SurePath LBC (p = 0.0026). In the secondary outcome analysis, the sensitivity of conventional smears vs forceps biopsies was 60.53% vs 78.95% (p = 0.046) and 81.82% for both SurePath LBC vs forceps biopsies (p = 0.724). The specificity of both cytological examination and forceps biopsies was 100%.

Conclusion: SurePath LBC was a more reliable test than conventional smears. Moreover, its diagnostic performance was close to that of forceps biopsies.

Keywords: Cytology, Biliary tract neoplasm, ERCP