血浆游离DNA(cfDNA)是最新开发诊断试剂和疾病预后的研究热点，研究集中在cfDNA的突变、表观遗传变化和DNA完整性等变化上。乙肝病毒常整合在宿主基因组中，整合又存在重复靶基因。靶基因与HBV整合后与肝癌的发生发展密切相关。课题组开发了新的文库构建方法和一种大规模锚定并行测序技术，对原发性肝癌组织中HBV整合位点进行研究，发现14个新的HBV重复整合靶基因。鉴此，提出假说：cfDNA含有原发癌细胞中HBV整合宿主DNA的重复整合位点。拟将：1）比较正常人、慢性乙肝病毒感染者、肝硬化病人和肝癌病人cfDNA中的HBV整合位点；2）比较不同病理分期肝癌病人cfDNA中的HBV整合位点；3）比较术前术后或治疗前后肝癌病人cfDNA中HBV整合位点。预期得到cfDNA中HBV整合宿主DNA重复整合位点作为肝癌辅助诊断和监测、疗效跟踪和预后判断的应用方法，对降低我国肝癌病人的死亡率有重要价值。

Circulating free DNA (CfDNA) is becoming a hotbed for developing novel diagnosis and prognosis methods for human diseases. In cancer research, the major focuses are on mutations, epigenetic changes, loss of heterozygosity and changes in DNA integrity in cfDNAs. In hepatocellular carcinomas (HCC), HBV virus often integrates into host genomes, and these integrations have recurrent target genes. The integration of HBV into these recurrent genes could results in expression changes related to liver carcinogenesis, and could also serve as diagnostic methods for HCC. Recently, We have developed and pubished a novel method of library construction and a method of massive anchored parallel sequencing (MAPS), which results in the identification of 14 novel recurrent target genes for HBV integration. .Hereby, we propose a hypothesis that cfDNAs could harbor HBV recurrent target sites derived from their original HBV liver tumors. Our aims are: 1) to compare the HBV recurrent target sites in cfDNAs among normal individuals, HBV chronic carriers, liver cirrhosis patients, and HBV-related HCC patients; 2) to correlate HBV recurrent target sites in cfDNAs with different pathological stages of HCCs; 3) to compare changes in HBV recurrent target sites in cfDNAs before and after surgery of treatment of HCCs. We expect to develop a method of using HBV recurrent target sites in cfDNAs for HCC diagnosis, treatment response monitoring and prognosis, which would be quite valuable for reducing deaths caused by HCC in China.