Proton beam therapy is a new type of radiation therapy for liver cancer. Research suggests that it may be equally effective as traditional radiation therapy but cause fewer side effects.

Proton beam therapy, or proton therapy, uses protons to destroy cancer cells instead of X-rays like traditional radiation therapy. Healthcare professionals have used it to treat cancer in clinics since the 1950s, but significant technological advances occurred during the 2010s.

Proton beam therapy may cause less damage to healthy tissue and fewer side effects than traditional radiation therapy. Research from 2020 suggests that it offers excellent long-term tumor management for people with liver cancer.

As of now, proton beam therapy is still available only at a few clinics and is more expensive than traditional radiation therapy.

Read on to learn more about how proton beam therapy treats liver cancer and who might benefit from it.

Proton beam therapy uses an external machine to aim protons at your cancer cells. Protons are positively charged particles that can destroy cancer cells when they’re accelerated to high speeds. The energy from these particles destroys cancer cells by damaging their DNA.

In traditional radiation therapy, X-rays emit energy along the entire path they travel. A large percentage of their energy passes through the tumor. Radiation that passes through the tumor is called the exit dose. The exit dose can cause low to moderate damage to healthy tissue.

Protons release their energy at a specific distance over a short range, potentially limiting damage to healthy cells. They produce almost no exit dose.

As of now, there’s still a lack of research about who makes the best candidate for proton therapy. But proton therapy shows excellent outcomes in both older and younger adults.

Research studies from 2018 in Japan suggest the benefits of proton therapy in a selected group of people who had liver cancer with a large tumor or liver cancer with portal vein thrombosis.

People who don’t make good candidates for traditional radiation therapy because of a high likelihood of radiation-induced liver disease may be better suited for proton beam therapy than people who aren’t at high risk.

Proton therapy may be beneficial for people with the most common type of liver cancer, hepatocellular carcinoma, and a condition called portal vein tumor thrombosis that’s linked to poor outcomes.

This condition occurs when the tumor extends into the central vein that drains blood from your gastrointestinal tract to your liver.

The primary advantage of proton beam therapy over traditional radiation therapy is that it’s linked to lower rates of side effects but comparable survival rates. Many studies suggest excellent long-term tumor management.

Multiple studies from Japan, Korea, and the United States have reported 5-year local control rates of around 80–95% for people with liver cancer treated with proton therapy.

The 5-year local control rate is the percentage of people with a smaller tumor 5 years after their treatment than at the beginning of their treatment.

In a 2020 study based in the United States and Taiwan, researchers found that proton beam therapy shows high rates of local control and overall survival for medium-to-large tumors that couldn’t be removed surgically.

The researchers reported that half of the 46 people in their study lived at least 30.7 months.

In a 2017 study from Japan, researchers examined the long-term outcomes of people with previously untreated hepatocellular carcinoma. The researchers reported 5-year overall survival rates of:

5-year overall survival rate
Early stage69%
Intermediate stage66%
Advanced stage25%

In a 2023 study researchers found favorable survival rates without severe toxicity in people with liver cancer that spread to the bile ducts.


  • Cost: Proton therapy is more expensive than traditional radiation therapy, and not all insurance companies provide coverage since there’s limited research showing that it provides additional benefits for liver cancer.
  • Availability: Proton therapy requires expensive technology that’s only available at a few facilities. As of April 2019, there were only 31 proton therapy facilities in the United States and 81 worldwide. Another 41 were under construction.
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Proton therapy usually causes fewer side effects than regular radiation therapy since the radiation more specifically targets cancer cells.

In a 2020 study, researchers compared the side effects and overall survival rates among 1,483 people with locally advanced liver cancer who received chemotherapy and radiation therapy.

Of the people in the study, 391 received proton therapy and 1,092 received traditional radiation therapy.

The researchers found that proton therapy showed a significantly lower likelihood of side effects within 90 days, but there was no difference in overall survival.

In another 2020 study, researchers reported the following rates of complications among 46 people with liver cancer who received proton beam therapy:

Proton therapy is a relatively new but promising treatment for liver cancer. Researchers are continuing to examine how to use it best and who might benefit from it most. It usually causes fewer side effects than traditional radiation therapy.

Proton therapy is only available at a few treatment centers in the United States. But the technology is becoming more readily available as researchers continue to find promising results.