2012年1月3日，据《每日科学》报道，多年以来，医生们已经知道致命性肝癌的发病率正在逐年上升，但是究竟什么原因造成这种趋势仍然是个谜。最近发表于1月份Mayo Clinic Proceeding期刊上的2篇Mayo临床研究为肝癌（HCC）的上升趋势提供了一副较为清晰的图像。在美国，肝癌患者在过去的三十年中增加了3倍，在晚期阶段诊断的患者其5年生存率仅为10％至12％。
"这些研究阐明了在特定群体中鉴定出具有肝癌风险因素的个体的重要性，以在其早期可治疗阶段制伏疾病，"W. Ray Kim说，医师、胃肠病学和肝病专家及一项研究的首席研究员。
Kim博士的研究小组，调查了数十年来来罗切斯特流行病学项目的记录（一个数据库，涵括了整个国家的住院和门诊护理记录）。研究发现，肝癌的群体发病率（每10万人中有6.9个人）比基于国家癌症研究所数据（每10万人中有5.1个人）所预计的群体发病率要高。该研究还发现，肝癌，这个二十年前倾向于由肝脏疤痕的疾病如酒精所致肝硬化引起，现在则由丙型肝炎病毒感染所致。
"丙型肝炎所致的肝脏疤痕经过20至30年后发展成癌症，"Kim博士说。"我们现在看到的50岁和60岁患者，在30年前就感染了丙型肝炎，而他们甚至不知道自己已经被感染了。"
11％ 的肝癌与肥胖有关，尤其是与脂肪肝。
"总体而言，这是一个很小的比例，"Kim博士说。 "但随着全国性肥胖的流行，我们相信肝癌的发病率在可预见的将来可能会显著地增加。"
另一项研究主要侧重于索马里群体，这个群体数量在美国不断增长，尤其是在明尼苏达州，在过去二十年中多达50,000名索马里人定居此地。东非国家乙型肝炎的患病率较高，而乙型肝炎是肝癌的危险因素。
研究人员调查了在Mayo临床生命科学系统的记录证实，乙肝仍然是一个危险因素，但他们同时惊奇地发现，在人群中相当比例的肝癌病例归因于丙型肝炎，这在之前未被认为有显著的普遍性。
"这项研究表明，丙型肝炎筛检将有助于索马里人群体，同时能够密切监测这些患者的肝癌风险。 " Mayo诊所的研究员、文章的第一作者Abdirashid Shire博士说，"这将大大改善这些索马里肝癌患者的治疗和生存。"
该研究是由美国国立卫生研究院和（NIH）Mayo诊所中心转化科学活动组支持。（生物谷bioon.com）
Risk Factors in Rising Trend of Liver Cancer Identified
ScienceDaily (Jan. 3, 2012) - Doctors have known for years that the incidence of deadly liver cancer is on the rise, but what is causing that trend has remained a mystery. Two recent Mayo Clinic studies published in the January issue of Mayo Clinic Proceedings offer a clearer picture of the rise of hepatocellar carcinoma (HCC), or liver cancer, which has tripled in the U.S. in the last three decades and has a 10 to 12 percent five-year survival rate when detected in later stages.
"The studies illuminate the importance of identifying people with risk factors in certain populations to help catch the disease in its early, treatable stages," said W. Ray Kim, M.D., a specialist in Gastroenterology and Hepatology and principal investigator of one study.
Dr. Kim's research group looked at several decades of records in the Rochester Epidemiology Project, a database that accounts for an entire county's inpatient and outpatient care. The study found the overall incidence of HCC in the population (6.9 per 100,000) is higher than has been estimated for the nation based on data from the National Cancer Institute (5.1 per 100,000). The study also found that HCC, which two decades ago tended to be caused by liver-scarring diseases such as cirrhosis from alcohol consumption, is now occurring as a consequence of hepatitis C infection.
"The liver scarring from hepatitis C can take 20 to 30 years to develop into cancer," Dr. Kim says. "We're now seeing cancer patients in their 50s and 60s who contracted hepatitis C 30 years ago and didn't even know they were infected."
Eleven percent of cases were linked to obesity, in particular fatty liver disease.
"It's a small percentage of cases overall," Dr. Kim says. "But with the nationwide obesity epidemic, we believe the rates of liver cancer may dramatically increase in the foreseeable future."
Another study looked exclusively at the Somali population, which is growing in the U.S., particularly in Minnesota, where as many as 50,000 Somalis have settled in the last two decades. The East African country is known to have a high prevalence of hepatitis B, a risk factor for HCC.
Researchers investigating records in the Mayo Clinic Life Sciences System confirmed that hepatitis B remains a risk factor, but they were surprised to find that a significant percentage of liver cancer cases in the population are attributable to hepatitis C, which had not been known to be significantly prevalent.
"The study suggests that screening for hepatitis C would be helpful for the Somali population and would enable close surveillance of liver cancer among those at risk," says lead author Abdirashid Shire, Ph.D., a Mayo Clinic researcher. "That would greatly improve treatment and survival of Somalis with this type of cancer."
The studies were funded by the National Institute of Health and the Mayo Clinic Center for Translational Science Activities.
