Familial aggregation of hepatocellular carcinoma (HCC), the third leading cause of cancer death worldwide, has shown to be a common phenomenon. We investigated the association between the genetic background and HCC familial aggregation. Serum samples were collected from HCC family members and normal control family members for screening the differentially expressed protein peaks with the approach of surface-enhanced laser desorption ionization time-of-flight mass spectrometry. Potential genetically associated protein peaks were selected and further identified by matrix assisted laser desorption ionization-time of flight mass spectrometry. A panel of six protein peaks (m/z 6432. 94, 8478.35, 9381.91, 17284.67, 17418.34, and 18111.04) were speculated to reflect the genetic susceptibility of HCC familial aggregation. Three of them (m/z 6432.94, 8478.35, and 9381.91) were selected to identify as the candidate proteins. Nine identified proteins, including mostly apolipoprotein family (ApoA1, ApoA2, ApoC3, ApoE) and serum amyloid A protein (SAA), were found overexpressed in the multiple HCC cases family members. The comparative proteomic profiles have suggested that genetic factors ought to be taken into account for familial aggregation of HCC. (Cancer Sci 2012; 103: 1833-1838 H epatocellular carcinoma (HCC) is one of the most commonly diagnosed cancers, and ranks the third cause of cancer related death in the world (9.2% of the total).(1,2) Among different geographical regions, large variation of morbidity and risk factors were observed, with the highest rate in Asian, and lowest rate in the US as well as Europe countries.(3,4) Hepatitis B virus (HBV) infection, hepatitis C virus (HCV) infection, and chronic exposure to aflatoxin play crucial roles in hepatocarcinogenesis among Asian people, while fatty liver disease and high consumption of alcohol are the dominant causes among low incidence regions.(5,6) The HCC incidence rate is remarkably high in China, accounting for approximately 55% of annual new cases in the world.(7) Particularly in Guangxi province of China, an endemic area of HBV infection, the HCC mortality has risen as the first cause of malignant cancer-relative death. (8) It is well-accepted that HBV infection constitutes the main etiological factor of HCC, while the process of hepatocarcinogenesis integrates multi-stages and multi-factors, including interactions of HBV, chemical carcinogen, and genetic susceptibility.(9) In addiction, the literature conveys that the lifetime risk of developing HCC for HBV infected individuals has been estimated to be 40%, (10) implying that a wide individual discrepancy exists in the HCC susceptibility, and that environmental factors alone are insufficient to fully address the familial aggregation of HCC. (11,12) We have observed that most HCC occurs obviously in clusters by geographical distribution or by family aggregation in Guangxi, China. Family aggregation of HCC has received researchers' attention for decades. Pedigree studies are frequently carried out to val...