Epidemiologic Study of Cancer in Koreans in Japan

为了阐明在日本的韩国人患肝癌风险高的原因，我们进行了流行病学研究，同时关注3组人群中丙型肝炎病毒（HCV）基因型和细胞色素P-450 2 E1（CYP 2 E1）基因型的分布，以及肝细胞癌（HCC）的发生与HCV和CYP 2 E1基因型之间的关系;在韩国的韩国人，在日本的韩国人和日本人在这项为期3年的韩国-日本联合研究中发现，HCV基因型3在HCC患者和韩国人的献血者中流行。另一方面，HCV基因型2在日本的日本人和韩国人的HCC患者和献血者中普遍存在。因此，在日本的韩国人表现出了类似的分布的HCV基因型的lof Japanese.We接下来进行了一项病例对照研究之间的关联HCC的发展和HCV基因型在大坂医学中心癌症和心血管疾病，大坂大学。结果发现，HCV基因型2比HCV基因型3和4显示出更高的肝硬化和HCC的发展风险。CYP 2 E1是唯一代谢N-亚硝基二甲胺的酶，N-亚硝基二甲胺是一种有效的肝癌原。CYP 2 E1基因型与二乙基亚硝胺诱发肝癌的个体易感性有关，长期服用乙醇可加速这种易感性，但在韩国和日本HCC患者中CYP 2 E1基因型分布无差异。CYP 2 E1基因型c1/c2和c1/c2比CYP 2 E1基因型c1/c1显示出更高的肝癌发生风险，但差异无统计学意义。总之，HCV基因型2在日本的韩国人中普遍存在，这可能因此在其肝癌发生风险增加中发挥作用。

In order to clarify the reasons why Koreans in Japan demonstrate a high risk for developing liver cancer, we have been carrying out epidemiological studies, while focusing on the distribution of hepatitis C virus (HCV) genotypes and cytochrome P-450 2E1 (CYP2E1) genotypes, and the relationships between the development of hepatocellular carcinoma (HCC) and the genotypes to HCV and CYP2E1 among 3 groups ; Koreans in Korea, Koreans in Japan and Japanese in this 3-year Korea-Japan Joint Study.HCV genotype 3 was found to be prevalent among HCC patients and blood donors of Koreans in Korea. On the other hand, HCV genotype 2 was prevalent among both HCC patients and blood donors of both Japanese and Koreans in Japan. Koreans in Japan thus demonstrated a similar distribution of HCV genotypes to that lof Japanese.We next conducted a case-control study on the association between the development of HCC and HCV genotypes at the Osaka Medical Center for Cancer and Cardiovascular Diseases, and Osaka University. As a result, HCV genotype 2 was found to show a higher risk for the development of liver cirrhosis and HCC than HCV genotypes 3 and 4.CYP2E1 is the only enzyme that metabolizes N-nitrosodimethylamine, a potent hepatocarcinogen. CYP2E1 genotype is related to individual susceptibility to diethlnitrosamine-induced liver cancer, and this susceptibility was observed to be accelerated by long-term administration of ethanol.No difference was observed in the distribution of CYP2E1 genotypes between HCC Koreans and Japanese patients. CYP2E1 genotype c1/c2 and c1/c2 showed a somewhat higher risk for the development of HCC than CYP2E1 genotype c1/c1, but the difference was not statistically significant.In conclusion, HCV genotype 2 was prevalent among Koreans in Japan, which may thus play a role in their increased risk for developing HCC.