If you make it a habit to down a cup of coffee each day, you may be doing yourself a favor. Doctors in a new study claim coffee-drinking may help you lower your risk of developing liver cancer.¹ However, the researchers add that the drink's protective effect may not be as strong for those infected with hepatitis.

They initiated their study as an extension of previous positive epidemiologic research on the possible relationship between coffee consumption and liver cancer, explained the study's lead investigator, Taichi Shimazu, MD, in the Division of Epidemiology at the Tohoku University Graduate School of Medicine in Sendai, Japan.

Coffee and Cancer
Shimazu and a group of fellow epidemiologists reviewed collective data from two previous, large studies on coffee consumption in that country. In all, more than 60,000 people had taken part in these two studies.  "A self-administered questionnaire about the frequency of coffee consumption and other health habits was distributed to 22,404 subjects in Cohort 1 and 38,703 in Cohort 2, aged 40 years or more, with no previous history of cancer," wrote Shimazu and his colleagues.

In their data analysis, the research team identified 70 cases of liver cancer among the study participants from the first group, and 47 cases of the disease from those in the second group. Each individual had been followed for a total of seven years.

After taking other potential liver cancer risk factors into account, such as age, alcohol consumption and smoking, the researchers estimated that those who never drank coffee faced the highest risk of cancer, compared to those who drank at least one cup of coffee per day. Even those who drank coffee occasionally had a lower risk than never-drinkers, the study found. Regular drinkers had a 29% lower risk than occasional drinkers, but a more than 40% reduced risk than those who never drank coffee.

In addition, "in the subgroup of subjects with a history of liver disease, we found a significant inverse association between coffee consumption and the risk of liver cancer," the study team wrote.

Consistently Positive Conclusions
The study's findings add credence to research published earlier this year in Italy that also found drinking coffee had benefits for protecting people from liver cancer.²  In that analysis, doctors at a hospital in northern Italy evaluated the risk of liver cancer among 250 patients with the disease compared to 500 without it, relative to coffee consumption. Using a standard questionnaire, the participants were asked to submit information on their coffee-drinking habits in the previous ten years.

After analyzing each person's risk of liver cancer, as well as their coffee-drinking habits, the researchers concluded that the risk of cancer decreased incrementally with increasing coffee consumption. Compared to those who had never drank coffee, those who reported drinking at least five cups per day had the lowest risk—approximately a third that of non-drinking patients. However, those with liver cancer caused by hepatitis had milder reduced risks, the study authors found.

Nonetheless, coffee-drinking was associated with a lower risk of liver cancer, regardless of its underlying cause, they wrote.

Yet another study published earlier this year echoed these conclusions.³ Researchers with the National Cancer Center in Tokyo conducted a prospective cohort study similar to the latest research on the prophylactic effects of coffee. The investigators identified patients diagnosed with hepatocellular carcinoma from a large, unrelated prospective study in Japan. Data on their regular coffee consumption was collected, as well as their type of hepatitis infection, sex, age, diet, lifestyle factors and previous history of liver disease.

The research team found that people who consumed coffee nearly each day at the minimum cut their risk of contracting hepatocellular carcinoma by more than half, on average. Additionally, increasing amounts of coffee consumption decreased the risk even further, the investigators reported, with the greatest risk reduction associated with drinking at least five cups of coffee daily.

"The risk of liver cancer in almost never drinkers in this population was 547.2 cases per 100,000 people over 10 years," they wrote. "But it was 214.6 cases per 100,000 people with drinking coffee on a daily basis."

Hepatitis Implications
Shimazu has a warning for people at risk of contracting liver cancer from hepatitis infection, however. "Because there is a strong association between these virus infections and the risk of liver cancer, we cannot exclude the possibility of overestimation of the effect of coffee consumption on the decreased liver cancer risk," he stated. The effect of coffee on liver cancer risk in hepatitis-infected people was not investigated in his study, he added, and thus more research on that aspect of the risk is necessary.

Further, the specific compounds in coffee that might be beneficial against liver cancer risk aren't known yet, either, Shimazu pointed out. At least one study has suggested that cholorgenic acid, which is found in the beverage, may have potential cancer-fighting properties.⁴ Meanwhile, he says if further animal studies confirm these findings, an "interventional study in the clinical setting will be needed."

Liver Cancer 101
The most common form of liver cancer is hepatocellular carcinoma. While the exact cause of liver cancer isn't known, medical experts say certain factors put you at risk. Chronic hepatitis infection is one of those risk factors, as well as liver cirrhosis. While these conditions may not cause symptoms, blood tests can show doctors whether or not the hepatitis virus is present.⁵ Symptoms of the disease include pain in the upper right abdominal area, a swollen abdomen, weight loss, loss of appetite and feelings of fullness, weakness or fatigue, nausea and vomiting, jaundice, or fever.⁶

1. Shimazu T, Tsubono Y, Kuriyama S et al. Coffee consumption and the risk of primary liver cancer: pooled analysis of two prospective studies in Japan. Int J Cancer 2005 Aug 10;116(1):150-4.
2. Gelatti U, Covolo L, Franceschini M et al. Coffee consumption reduces the risk of hepatocellular carcinoma independently of its aetiology: a case-control study. J Hepatol 2005 apr;42(4):528-34.
3. Inoue M, Yoshimi I, Sobue T, Tsugane S; JPHC Study Group. J Natl Cancer Inst 2005 Feb 16;97(4):293-300.
4. Shimizu M, Yoshimi N, Yamada Y et al. Suppressive effects of chlorogenic acid on N-methyl-N-nitrosourea-induced glandular stomach carcinogenesis in male F344 rats. J Toxicol Sci 1999 Dec;24(5):433-9.
5. National Cancer Institute. Liver Cancer: Who's at Risk? Available at: http://www.cancer.gov/cancertopics/wyntk/liver/page4. Accessed August 25, 2005.
6. National Cancer Institute. Symptoms. Available at: http://www.cancer.gov/cancertopics/wyntk/liver/page5. Accessed August 25, 2005.

John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.