WEDNESDAY, March 11, 2020 (HealthDay News) -- People with hepatitis B or C are at greater risk for liver cancer, but a low-dose aspirin a day might significantly lower that risk, a new study suggests.

Over a median of nearly eight years of follow-up, 4% of those taking low-dose aspirin developed liver cancer, compared with 8.3% of those not taking the drug, researchers found.

"It's not clear how aspirin works to prevent liver cancer," said lead researcher Dr. Tracey Simon, an instructor at Harvard Medical School in Boston.

Simon cautioned that this study cannot prove that aspirin prevents liver cancer. Only an association was seen in the study.

But "aspirin may have anti-inflammatory properties that extend beyond its cardiovascular protective effects," she suggested.

In other studies, aspirin has been linked to less liver fat, inflammation and scar tissue, Simon added. All of these are signs of potential liver disease, including cancer. "Aspirin stops or delays the progression of liver disease," she said.

Still, Simon said that although the findings are promising, they're not definitive, and no one should start taking aspirin in the hopes of preventing liver cancer.

"What we really need is a randomized clinical trial in order to say to patients that this would give them benefit without causing harm," she said.

For the study, Simon and her colleagues used Swedish registries to identify more than 50,000 people with hepatitis B and C who were not taking low-dose aspirin, and more than 14,000 who were. Those taking aspirin were doing so to prevent heart attacks and strokes.

Aspirin users were found to have lower liver cancer risk. The researchers also found that the longer someone took aspirin, the greater the reduction in the risk for liver cancer.

Also, the risk of dying from liver disease over 10 years was 18% among those who didn't take aspirin and 11% among those who did, the researchers found.

And while aspirin can cause internal bleeding, Simon's team found that the risk for bleeding was similar among aspirin users and nonusers (8% and 7%).

Eric Jacobs is senior scientific director for epidemiology research at the American Cancer Society. "The lower rate of liver cancer observed in low-dose aspirin users in this study is intriguing," he said.

But people who are prescribed low-dose aspirin may differ from those who are not in ways that make them less likely to develop liver cancer, said Jacobs, who wasn't part of the study.

For example, people with severe liver cirrhosis, which is a risk factor for liver cancer, may be less likely to be prescribed aspirin because of concerns about aspirin-induced bleeding, he explained.

Also, the findings do not apply to people who do not have hepatitis, Jacobs noted.

"A randomized trial of aspirin in people with hepatitis would be needed to more definitively determine if low-dose aspirin can help prevent liver cancer or fatal liver disease in this group," Jacobs said.

Aspirin can have both risks and benefits, he added.

"People who are wondering if they should start taking aspirin should first talk to a health care provider, who will be able to take their personal medical history into account," Jacobs said.

Although rates of liver cancer have been increasing in the United States, people can reduce their risk, as well as risk of other cancers and serious diseases, by not smoking and maintaining a healthy weight, he said.

"A one-time blood screening test for hepatitis C is also recommended for all Americans born between 1945 and 1965, as early treatment can help reduce liver damage," Jacobs added.

The report was published March 12 in the New England Journal of Medicine.

More information

The American Cancer Society offers more on liver cancer.