美国机构:为什么肝癌患者数量还在增加?

    美国近年度政府报告中报告了有关癌症发展趋势的好消息：20世纪90年代早期，癌症的总体死亡率一直在下降，2003年至2012年期间继续下降。

但是该报告还存在一个令人担忧的例外：同一时期肝癌的死亡率每年增长了2.7%，20世纪80年代以来，持续保持上涨趋势。

    原发性肝癌是一种源于肝脏自身，而不是从其他器官转移到肝脏的恶性肿瘤。据推断今年诊断为原发性肝癌的患者有39230人，其中27170人死于该疾病，通常情况下该疾病不易被检测直到其发展为晚期。男性患原发性肝癌的发生率是女性的2倍。

    特定人群中的发病率为严峻-即出生于1945年至1965年间的婴儿潮。从2008年至2012年，在50岁以及50岁以上的患者中肝癌导致的死亡每年增加3.5%，但是在小于50岁的成人中死亡率每年降低3.9%。

上述差异与感染丙肝病毒、HCV等重要风险因素有关。其他的风险因素包括乙肝病毒（HBV）感染、肝硬化、大量饮酒、肥胖、糖尿病和吸烟。虽然1982年以来已经有HBV疫苗，但是没有针对HCV的预防疫苗。

丙型肝炎病毒感染在20世纪60年代至20世纪80年代期间，在发现病毒以及发现其通过输送受感染的血液和使用注射药物之前处于高水平。自那时起，HCV筛查已减少了感染率，如果诊断为HCV，就会使用抗病毒药物进行治疗，以减少肝癌的风险。

联邦指南指出应筛查HCV感染高风险的人群，且在2012年提出一个建议，即要对1945年至1965年期间出生的成人定期进行HCV筛查。然而，一项2013年的研究发现，婴儿潮仅有12.3%的人数报告进行过这种检测。根据Anuj Patel医生（丹娜法伯胃肠道癌症中心的一位医学肿瘤学家）报告，当大多数患者出现活动性或慢性肝脏疾病的某些症状，仅仅可诊断为HCV感染。

Patel强调HCV筛查的重要性，并且说道早期诊断可帮助早期治疗HCV感染，并指出2013年以来批准的5种不同口服药物的联合用药非常有效且耐受。早期诊断还可以帮助早期检测慢性HCV感染的并发症，其中包括肝癌。已发现上述措施可改善结局和生存率。

HCV感染约占肝癌的20%，终由于人口因素、筛查和治疗，流行病将慢慢减少。尽管如此，某些数字模型预测肝癌的发生率将继续上升几十年；此外病毒以及风险因素如肥胖、脂肪肝和糖尿病等也在不断流行。

    美国疾病控制与预防中心主任Tom Frieden在该报告发布的声明中说道：“肝癌日益沉重的负担令人担忧。我们需要做更多的工作来促进肝炎治疗和疫苗。”

Why Is Liver Cancer on the Rise?

There was mostly good news in the most recent annual government report on cancer trends in the United States: Overall death rates, which have been dropping since the early 1990s, continued to decline between 2003 and 2012.

But the report focused on a disturbing exception: The death rate for liver cancer during that same period increased by 2.7 percent per year, maintaining an upward rise since the 1980s.

Primary liver cancer – that which develops in the liver as opposed to metastasis from another organ – is projected to be diagnosed in 39,230 individuals this year, and 27,170 deaths are expected from the disease, which typically isn’t detected until it is in advanced stages. The cancer affects twice as many men as women.

The rise is steepest in a particular population – baby boomers born between 1945 and 1965. From 2008 to 2012, deaths caused by liver cancer increased 3.5 percent per year among those 50 and older, but decreased 3.9 percent per year among adults younger than 50 years of age.

These disparities are related to an important risk factor for liver cancer – infection with the hepatitis C virus, HCV. (Other risk factors include infection with hepatitis B virus (HBV), cirrhosis, heavy alcohol use, obesity, diabetes, and smoking.) Although an HBV vaccine has been available since 1982, there is no preventive vaccine for HCV.

Hepatitis C virus infection was at its highest levels during the 1960s to 1980s, before the virus was discovered and found to be transmitted through contaminated blood transfusions and use of injected drugs. Since then, HCV screening has reduced infections and if diagnosed, it can be treated with antiviral drugs, reducing the risk of liver cancer.

Federal guidelines say people at high risk for HCV infection should be screened, and in 2012 a recommendation was issued for one-time HCV screening of adults born between 1945 and 1965. A 2013 study, however, found that only 12.3 percent of baby boomers reported having had the test. “Most patients only get a diagnosis of HCV infection when they present with some symptom of active or chronic liver disease,” according to Anuj Patel, MD,a medical oncologist inDana-Farber’s Center for Gastrointestinal Cancer .

Emphasizing the importance of HCV screening, Patel said that early identification allows for early treatment of HCV infection, noting that five different combinations of oral drugs approved since 2013 are highly effective and well-tolerated. Early identification also allows for early detection of complications of chronic HCV infection, including liver cancer, and these measures have been found to improve outcomes and survival.

HCV infection is responsible for about 20 percent of liver cancers, and eventually the epidemic will wane as a result of demographic factors, screening and treatment. Still, some mathematical models predict that incidence of liver cancer will continue to climb for several decades; in addition to the virus, risk factors like obesity, fatty liver disease, and diabetes are becoming more prevalent.

“The growing burden of liver cancer is troublesome,” said Tom Frieden, MD, director of the U.S. Centers for Disease Control and Prevention, in a statement when the report was released. “We need to do more work promoting hepatitis, treatment, and vaccination.”

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