SURGE IN LIVER CANCER IN HIGH INCOME COUNTRIES

The incidence of liver cancer and deaths from the disease have doubled since the early 1990s in several high-income countries, including the United States, Canada, Australia, and the United Kingdom.

Liver cancer is the only major cancer where mortality is increasing in these countries, new findings indicate.

"Many of these liver cancers strike people in their 50s when they are still of working age," Morris Sherman, MD, emeritus professor of medicine, University Health Network and the University of Toronto, Ontario, Canada, said in a statement.

"The prospects for surviving liver cancer are bleak, so our only hope is to intervene early and prevent the cancer happening in the first place or to find early curable cancers," he added.

The topic was discussed during the Global Hepatitis Summit 2018 in Toronto.

Data for an age-standardized incidence rate per 100,000 population show that liver cancer rates have increased sharply in all four countries since the early 1990s.

Overall, the highest incidence is in the United Kingdom, at an age-standardized incidence rate of 9.6 per 100,000 in 2015, followed by 9.2 per 100,000 in the United States, 7.4 per 100,000 in Australia, and 6.0 per 100,0000 in Canada.

Deaths from liver cancer have similarly increased among men and women, again based on age-standardized death rates per 100,000 population.

In 2014, the age-standardized mortality rate was 8.7 per 100,000 population in the United Kingdom, while in 2015 the age-standardized mortality rate was 6.6 per 100,000 in both the United States and Australia and 7.5 per 100,000 population in Canada.

Surge in Liver Cancer

Sherman told the audience that the reasons for the surge in liver cancer incidence, and the increase in mortality, include infection with hepatitis B and hepatitis C virus, as well as the obesity epidemic.

The obesity epidemic is fueling an epidemic of nonalcoholic fatty liver disease (NAFLD), which can progress to liver cancer, he explained.

Even in high-income countries such as the United States, many people are unaware that they have been infected with hepatitis B or C virus; by the time they present with symptoms, it's often too late to offer any curative treatment.

Although new directly acting antiviral drugs (DAA) have transformed the management of hepatitis C — effectively curing 95% of all patients who are treated with DAAs — the same progress has not been made with hepatitis B. However, there are drugs that can help prevent progression to liver cancer in many patients.

The obesity epidemic that is causing increasing numbers of patients to develop NAFLD is nowhere near under control, Sherman commented. For example, an estimated 20% of the population in developed countries has some level of NAFLD. Of these, 1 in 10 could progress to cirrhosis, of whom 20% to 30% could develop liver cancer.

"We are seeing more liver cancer related to NAFLD now than we were, say, 10 years ago," he told Medscape Medical News.

"And it's also quite likely in the future that NAFLD will be the bigger driver of liver cancer because hepatitis C will be adequately managed," he added.

Part of the problem with hepatitis B and hepatitis C is the aging of the infected population.

"The longer you have the infection and the older you are, the more likely you are to develop liver cancer," Sherman explained. "So people who acquired hepatitis C infection in the 1950s and 60s are now getting to an age where cancer starts to be more likely, and the same applies to hepatitis B," he said.

Indeed, in early June 2018, the Canadian Association for the Study of the Liver published guidelines recommending that individuals born between 1945 and 1975 — the baby boomers — be tested for hepatitis C.

The reasoning behind this is that somewhere between two thirds and three quarters of people with hepatitis C, at least in Canada, were born between 1945 and 1975.

Anywhere from 40% to 70% of those who are infected with hepatitis C virus are unaware that have been infected because it can take many years before symptoms become apparent.

"This is why this recommendation to screen baby boomers is so important," Sherman said.

"Because it's not only that this [age] category has the highest prevalence of hepatitis C but it's also because they are the highest risk within this category because of the duration of infection," he added.

However, not everyone infected with hepatitis B or C virus or who has developed NAFLD is at significant risk for liver cancer, Sherman underscored.

"You can't screen everybody," he said.

"But there are a variety of risk scores that can be used to identify those at high risk for the disease, and you can use clinical features, the most significant of which is the presence of cirrhosis," Sherman noted. "If a patient has cirrhosis, their risk of liver cancer is considerably higher than if they do not have cirrhosis," he added.

Once cirrhosis is diagnosed, patients go into a screening program where they undergo ultrasonography every 6 months.

"Caught early, liver cancer is largely curable," Sherman said.

"And we could make a huge impact on future liver cancer rates by investing more resources in screening and diagnosis of hepatitis B and C," he predicted.

In 2012, an estimated 745,000 people died of liver cancer worldwide.

Sherman reports that he has served as a consultant for Gilead Sciences.

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