The Significance of p53 and K-ras Immunocytochemical Staining in the Diagnosis of Malignant Biliary Obstruction by Brush Cytology during ERCP.
OBJECTIVE
Brush cytology during ERCP can provide a pathologic diagnosis in malignant biliary obstruction. K-ras and p53 mutations are commonly found in biliary and pancreatic cancers. We evaluated the diagnostic yield of brush cytology and the changes obtained by adding p53 and K-ras staining.


METHODS
One hundred and forty patients with biliary obstruction who underwent ERCP with brush cytology during a 7-year period were included. The sensitivity and specificity of brush cytology only and with the addition of p53 and K-ras staining were obtained.


RESULTS
Malignant biliary obstruction was confirmed in 119 patients. The sensitivity and specificity of brush cytology were 78.2% and 90.5%, respectively. The sensitivity of cytology was 77.3% at the ampulla-distal common bile duct (CBD), 92.6% at the mid common hepatic duct (CHD), and 94.7% at the proximal CBD-CHD (p<0.05); these values did not differ with the degree or the length of the obstruction. In the 97 patients who received additional p53 and K-ras staining, the sensitivity of cytology plus p53 was 88.2%, cytology plus K-ras was 84.0%, and cytology plus p53 and K-ras was 88.2%. The sensitivity of cytology plus p53 was higher than that of brush cytology only (95% confidence interval: 83.69-92.78 vs 72.65-83.65) but not that of cytology plus K-ras.


CONCLUSIONS
Brush cytology for malignant biliary obstruction has a high diagnostic accuracy. Adding p53 staining can further improve the diagnostic yield, whereas K-ras staining does not.
Kim
Young Sup
YS
Department of Internal Medicine, Catholic University of Daegu School of Medicine, Daegu, Korea.
Kim
Ho Gak
HG
Han
Jimin
J
Hur
Change Jae
CJ
Kim
Byeong Suk
BS
Jung
Jin Tae
JT
Kwon
Joong Goo
JG
Kim
Eun Young
EY
Cho
Chang-Ho
CH
Sohn
Yoon Kyung
YK