Frequency of loss of heterozygosity on chromosome 17 in intrahepatic cholangiocarcinoma

BACKGROUNDS/AIM: Intrahepatic cholangiocarcinoma is the second most common intrahepatic neoplasm. Carcinogenesis is believed to be a multistage process that occurs as a result of mutations in oncogenes and tumor suppressor genes. Loss of heterozygosity (LOH) is the phenotype of genetic instability which has been used as a tool for detecting genetic phenotype alterations. Large number of the molecular alterations have been described in human cancer. Among them, that of p53 is quite common. The aim of this study was to determine the frequency of LOH at chromosome 17p related with p53. METHODS: Twenty cases who underwent hepatic resection due to intrahepatic cholangiocarcinoma, were included. LOH was analysed with four microsatellite markers by PCR. For the clinicopathologic parameters, tumor size, differentiation, and metastasis were evaluated. RESULTS: Fifteen patients (75%) showed LOH at one of the loci at the least. Five patients were LOH-high and 10 were LOH-low. The highest frequency of LOH was observed at D17S5 by 38.9%. Those of TP53, D17S796 and D17S513 were 29.4%, 21.4% and 35.3%, respectively. In addition, LOH tended to be more frequent when the tumor is mass forming type, poorly differentiated, or has tumor emboli or vascular invasion. CONCLUSIONS: This study showed that LOH was positive in 75% on chromosome 17p in intrahepatic cholangiocarcinoma which was relatively frequent at D17S5.