The role of p27kip1 protein expression on the biological behavior of intrahepatic cholangiocarcinoma

Recent studies have reported that a decreased p27kip1 protein (p27) expression is associated with aggressive tumor behavior in several human malignancies. In this study, we examined the role of p27 expression in intrahepatic cholangiocarcinoma (ICC) and the noncancerous intrahepatic bile duct epithelium and assessed its association with clinicopathologic features, especially the influence of decreased p27 expression by the tumor on its prognosis as determined by immunohistochemistry. Almost all noncancerous bile duct epithelia show positive nuclear staining and reveal a faintly positive reaction in the cytoplasm. In 62 surgically resected ICCs, a variable degree of positive p27 nuclear staining is recognized. A subset (13 of 62 cases; 21.0%) of the carcinomas displayed cytoplasmic staining. We classified 62 cases into 2 groups, a low expression group ( < 50% of p27 nuclear positive cells) and a high expression group (greater than or equal to 50% of p27 nuclear positive cells), and tested for the association between positive expression and clinicopathologic features. We found that a low expression of nuclear p27 was correlated with positive vascular invasion (P < .05). The survival curve of the group with low p27 nuclear expression was significantly lower than that of the group with high p27 nuclear expression (P < .005). According to the multivariate analyses, low p27 expression can be considered an independent prognostic factor whose occurrence indicates a worse prognosis. We conclude that a decreased p27 expression adds an independent parameter that can be used when determining the prognosis of patients with ICC.