The short answer
Much of Japan's liver cancer has been linked to long-term hepatitis B and C infection. Vaccines and antiviral treatment have helped lower this risk. Alcohol and fatty liver disease also matter. For people at higher risk, regular liver checks can catch cancer early.
Long-term hepatitis B and C infection has been a major cause of liver cancer in Japan.
Hepatitis B vaccination and antiviral treatment can lower liver cancer risk.
Heavy alcohol use and fatty liver disease also raise the risk.
People at higher risk may be offered regular liver checks to catch cancer early.
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The full explanation.
The simple answer
Liver cancer in Japan is closely tied to long-term viral hepatitis, mainly hepatitis B and C. These infections slowly damage the liver over many years. Alcohol and fatty liver disease add to the risk. Here is the hopeful part. Vaccines, antiviral treatments, and healthy habits can prevent much of this damage. And regular checks can catch cancer early in people at higher risk.
Hepatitis: the leading cause
For decades, a large share of Japan's liver cancer has been linked to long-term infection with hepatitis B or hepatitis C. These viruses can live in the liver for years. They quietly cause inflammation and scarring. Over time, that damage can lead to cirrhosis, which is heavy scarring of the liver, and then to liver cancer.
Hepatitis C, in particular, drove much of Japan's liver cancer in the past. Many people were infected years ago and did not know it. The virus often causes no symptoms until serious damage has been done.
Progress through vaccines and antivirals
This is a story with real hope, because we have tools that work.
A vaccine protects against hepatitis B. Wide vaccination, especially of babies, prevents new infections. Over time, that lowers liver cancer rates.
Antiviral medicines have changed care completely. Treatment can control hepatitis B and cure most cases of hepatitis C. Calming or clearing the infection reduces liver damage. That lowers the risk of liver cancer. More people in Japan have now been tested and treated, and hepatitis-related liver cancer has been falling.
The lesson is powerful: when a cancer has an infectious cause, preventing or treating that infection can prevent cancer.
Alcohol and fatty liver
Not all liver cancer comes from hepatitis. Heavy alcohol use damages the liver and raises cancer risk. The risk is higher still when it comes on top of viral hepatitis. Excess weight is also becoming more common. So fatty liver disease, a buildup of fat in the liver, is a growing cause of liver damage worldwide, including in Japan.
These causes matter because they are becoming more common even as hepatitis fades. Limiting alcohol helps protect the liver. So does managing weight and related conditions.
Catching it early
Some people already have long-term liver disease or hepatitis. For them, doctors often recommend regular liver checks to look for cancer early. These are usually ultrasound scans and blood tests. Because the risk is higher in this group, the checks can find liver cancer when it is smaller and more treatable.
This is a form of targeted screening: not for everyone, but for those whose risk is known to be higher.
A changing mix of causes
Liver cancer shows how a disease's causes can shift over time. In Japan, hepatitis C once drove the large majority of cases. That share has been falling, thanks to testing, antiviral cures, and vaccination against hepatitis B. But as one cause fades, others grow. The main ones are alcohol-related liver damage, and fatty liver disease linked to excess weight and metabolic conditions. So prevention has to keep changing. Clearing hepatitis is a huge win. Protecting the liver now also means addressing weight, blood sugar, and alcohol. The overall lesson is hopeful. Liver cancer has many preventable causes, and progress on one front is real, even as new challenges appear.
What this means for you
Two simple questions are worth asking your doctor. Should I be tested for hepatitis B or C? And do I need the hepatitis B vaccine? Many infections go unnoticed. Testing can open the door to treatment that protects your liver.
If you have liver disease or a hepatitis infection, ask whether regular liver checks are right for you. For everyone, limiting alcohol and keeping a healthy weight support liver health. These steps will not remove all risk. But they meaningfully shift the odds.
Sources
- National Cancer Institute, liver cancer: https://www.cancer.gov/types/liver
- National Cancer Center Japan, liver cancer statistics: https://ganjoho.jp/public/qa_links/report/statistics/2025_en.html
- CDC, viral hepatitis: https://www.cdc.gov/hepatitis/
- World Health Organization, hepatitis: https://www.who.int/health-topics/hepatitis
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Common questions
What causes most liver cancer in Japan?
Much of Japan's liver cancer has been linked to long-term infection with hepatitis B or C viruses, which slowly damage the liver over years. Alcohol and fatty liver disease are other important causes.
Can liver cancer be prevented?
Many cases can be reduced. Hepatitis B vaccination prevents that infection, and antiviral medicines can treat hepatitis B and C, lowering liver damage and cancer risk. Limiting alcohol and managing fatty liver also help.
How is liver cancer caught early?
People with long-term liver disease or hepatitis may be offered regular checks, such as ultrasound scans and blood tests, to catch cancer early when it is more treatable.
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Last updated: 2026-08-05Next planned review: 2027-07-08
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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