The 2017 Report on the Status and Trends of Tumors in China shows that primary liver cancer is the 3rd most common malignant tumor and the 2nd leading cause of tumor death in China, with about 400,000 new cases and 380,000 deaths from liver cancer each year nationwide.
However, a recent study published in the Journal of the American Medical Association-Oncology (JAMA Oncology) has brought surprising information. The study found that the incidence of liver cancer maintains an upward trend globally, but has declined in Asian countries such as China.
Along with the celebration, one wonders – what is the reason behind this change?
Hepatocellular carcinoma rates in China have fallen over 25 years 1/3
In the above study, an analysis conducted by Professor Fitzmaurice and others found that liver cancer is the fourth most common cancer causing death after lung, colon, and stomach cancers, with 854,000 new liver cancers and 810,000 deaths worldwide in 2015. An analysis of the incidence of liver cancer in most regions of the world from 1990 to 2015 found that the global incidence of liver cancer increased by 75% over the 25-year period.
Specifically by region, age-standardized incidence rates for liver cancer show an increase of more than 100% in many high-income countries, including the United States, Canada, Australia, New Zealand, and most European countries.
In contrast, traditional regions with a high incidence of liver cancer (e.g., East Asia, West Africa, etc.) have seen a decline in incidence rates. In China, for example, the age-standardized incidence of liver cancer in China decreased by a full third between 1990 and 2015.
At the same time, a recent study published in Gastroenterology by Professor Wu Jie of Zhejiang University came to similar conclusions.
The study provides a detailed analysis of the incidence of liver cancer between 1983 and 2007. The study included patients with liver cancer from Asian countries such as China, Japan, Hong Kong, Singapore, the Philippines, and Thailand, as well as patients with liver cancer from Western countries represented by the United States and Australia, for a joint statistical analysis of incidence.
The results found that the incidence of liver cancer in China has decreased from about 20 per 100,000 to about 15 per 100,000 a very significant downward trend!
This study also found that although the baseline level of liver cancer incidence in China is still much higher than in the United States, we have made considerable improvements over the decades.
This is all due to our improving economy and effective hepatitis B prevention and control.
Both major causes of liver cancer in China have been effectively controlled
The most important factors in the development of liver cancer in China are hepatitis B virus infection and cirrhosis, and most cirrhosis evolves from hepatitis B. Therefore, hepatitis B virus infection is considered to be the most important cause of liver cancer.
In recent years, with the popularization of hepatitis B vaccination, the proportion of hepatitis B disease in China has been decreasing, and the incidence of liver cancer in all age groups has shown a significant decrease, thanks to the effectiveness of years of hepatitis B prevention and control.
In addition, aflatoxin, a toxin produced by certain fungi on agricultural crops, can be produced by corn, peanuts, cottonseed and nuts that have been left too long. Numerous studies have shown a direct relationship between aflatoxin and liver cancer.
In the past, China’s food industry was relatively backward, and people could not afford to throw away food that might have gone bad and continued to eat it after a little cooking, so the incidence of liver cancer was higher in some relatively economically backward areas.
With the improvement of China’s economy and public health awareness, people gradually stopped eating moldy food, and liver cancer caused by aflatoxin is gradually decreasing.
Other causes of liver cancer should not be taken lightly
While improvements in living standards and medical care have brought the two major causes of liver cancer under effective control, there are far more factors that contribute to the development of liver cancer than just these two.
The slowly increasing incidence of liver cancer in Europe and the United States continues to be a wake-up call, and other factors that contribute to the development of liver cancer are beginning to take on increasing importance.
Hepatitis C virus
Among the various hepatitis viruses, hepatitis C is an important cause of liver cancer in addition to hepatitis B. The Fitzmaurice study noted that hepatitis C virus caused the most new cases of liver cancer between 1990 and 2015.
Hepatitis C, like hepatitis B, is transmitted through blood, mother-to-child, and sexual routes, and there is no vaccine to prevent it. However, antiviral drugs can cure more than 95% of people infected with hepatitis C, thereby reducing deaths from liver cancer.
Alcohol
Alcoholic liver damage also has a place in liver cancer causation. a study by Fitzmaurice found that in 2015, hepatitis B infection and alcohol were the leading causes of liver cancer deaths worldwide, with the former accounting for 33% of deaths and the latter for 30%.
There was also a clear relationship between alcohol-caused liver cancer mortality and geography. In Eastern Europe, alcohol-attributable liver cancer deaths accounted for more than half of all liver cancer deaths in 2015. Among them, alcohol was the leading cause of liver cancer deaths in Belarus.
Gender
In terms of gender, both of these studies are consistent in concluding that men are more likely to get liver cancer than women.
Fitzmaurice found that in 2015 there were 203,000 cases of liver cancer caused by hepatitis B virus in male patients, while in female patients that number was less than half that of men.
Professor Jie Wu plotted a more detailed gender-specific incidence curve: the incidence in men was more than 2 to 3 times that in women, both in Asian countries (China, Japan, etc.) and in the United States and Australia.
Of course, the correlation between gender and liver cancer incidence may be only indirect, because men are more exposed to the risk factors for liver cancer because of work and socialization, which leads to a more pronounced gender bias.
There is a long way to go in the prevention and control of liver cancer in China
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Overall, the incidence of liver cancer has generally increased globally over the past 25 years, whereas countries in East Asia, such as China, have seen a significant decrease in incidence compared with the past, probably related to the widespread availability of hepatitis B vaccine and reduced intake of aflatoxin.
Professor Wu Jie believes that, assuming the current trend of hepatitis B vaccination continues, the incidence of liver cancer will continue to decrease in several East Asian countries, including China, until 2030; by 2030, it will be essentially at the same level of incidence as in developed countries, represented by the United States. By that time, China may be able to truly lift its “liver cancer powerhouse” hat.
For us, it’s important to get vaccinated against hepatitis B, get regular medical checkups, not eat moldy food, have safe blood transfusions and injections, and reduce alcohol consumption in our daily lives. All these details can help us stay healthy and away from liver cancer.