If pouring yourself a cup of coffee is part of your daily morning routine, you may have a lower risk of developing liver cancer—maybe. A new study published this month¹ suggested that those who drink coffee regularly may be less prone to developing hepatocellular carcinoma.

The study appears in the February 15 issue of the Journal of the National Cancer Institute.

"The inverse association between coffee drinking and hepatocellular carcinoma has been investigated from various aspects" in other research, said Shoichiro Tsugane, MD, one of the study's investigators in the division of Epidemiology and Biostatistics at the National Cancer Center in Tokyo, in an interview. But the results of this study were more "pronounced than those of previous studies," he said.

Hepatocellular carcinoma is the most common form of liver cancer in adults. It begins in the liver cells, called hepatocytes, and can have varying growth patterns.² Having hepatitis B or C or cirrhosis are among the risk factors for hepatocellular carcinoma. Symptoms include a hard lump on the right side just below the rib cage, discomfort in the upper abdomen on the right side, pain around the right shoulder blade, unexplained weight loss, jaundice, unusual fatigue, nausea, and loss of appetite.³

Coffee May Cut the Risk in Half
Tsugane and his colleagues at the National Cancer Center conducted a population-based cohort study of middle-aged and elderly Japanese subjects from the unrelated Japan Public Health Center-Based Prospective Study.  They based their research on previous animal studies that suggested that consuming coffee might have a protective benefit in this regard. "Epidemiologic evidence of such an association in a high-risk population is lacking," the scientists wrote.

Two hundred fifty men and 84 women newly diagnosed with hepatocellular carcinoma were followed during the study. They were grouped by whether or not they drank coffee, and were also classified by hepatitis virus infection, sex, age, diet, certain lifestyle factors, and previous history of liver disease.

They found that people who consumed coffee on a daily or nearly daily basis faced about half the risk of developing hepatocellular carcinoma compared with those who never drank coffee. The minimum to achieve this prophylactic effect was about 1 to 2 cups per day, Tusgane told Priority Healthcare.

Specifically, the research authors noted that the rate of liver cancer among those who never consumed coffee was about 547 cases per 100,000 people over 10 years. However, among daily coffee drinkers, the rate was about 214 cases per 100,000 people. The risk of hepatocellular carcinoma also decreased incrementally as more and more coffee was consumed, the Japanese scientists found.

The inverse relationship between coffee consumption and liver cancer risk persisted among those classified as being hepatitis B or C positive, and to individuals with no past history of chronic liver disease.

Is it Caffeine That's Responsible?
Why coffee has this beneficial effect isn't known. "Site specificity of the effect of coffee is another important issue that must be solved," Tsugane said.

The investigators caution that because decaffeinated coffee is rarely consumed in Japan, and no distinction was made between caffeinated and decaffeinated coffee in the study, it can't be determined if caffeine is responsible for the lowered risk of liver cancer. The results also need to be confirmed among people infected with hepatitis, the scientists stated. "In this study, the virus infection status at baseline was not determined," explained Tsugane. "Subjects with chronic liver disease may have reduced their coffee consumption to avoid the side effects of caffeine, and that may have led to a superficial decrease in hepatocellular carcinoma risk by coffee drinking. These should be determined in further studies."

What Other Scientists Have Said
A similar study was conducted by researchers in Milan, Italy 3 years ago.⁴ Physicians at Istituto di Ricerche Farmacologiche Mario Negri evaluated the effect of coffee drinking on the incidence of cirrhosis in a group of 101 patients with the disease compared to 1,538 individuals who were healthy.

Compared with the non-coffee drinkers, those who drank coffee faced lower odds of developing cirrhosis, and the more cups drunk per day, the lower the risk, the investigators found. The lowest risk was for those who had been drinking coffee daily for more than 40 years. Decaffeinated coffee, tea and cola-containing beverages, they found, had no effect.

"The present study confirms, and further quantifies, the existence of an inverse association between coffee consumption and liver cirrhosis. However, the metabolism of caffeine is impaired in fasting subjects with liver cirrhosis, and the association could be due to a reduction of coffee drinking in subjects with liver cirrhosis, " the research team wrote.

1. Inoue M, Yoshimi I, Sobue T, Tsugane S For the JPHC Study Group. Influence of coffee drinking on subsequent risk of hepatocellular carcinoma: a prospective study in Japan. J Natl Cancer Inst 2005 Feb 15;97(4):293-300.
2. American Cancer Society. What is Liver Cancer? Available at: http://www.cancer.org/docroot/cri/content/cri_2_2_1x_what_is_liver_cancer_25.asp. Accessed February 16, 2005.
3. National Cancer Institute. National Institutes of Health. General Information About Adult Primary Liver Cancer. Available at: http://www.cancer.gov/cancerinfo/pdq/treatment/adult-primary-liver/patient/. Accessed February 16, 2005.
4. Gallus S, Tavani A, Negri E, La Vecchia C. Does coffee protect against liver cirrhosis? Ann Epidemiol 2002 Apr;12(3):202-5.

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