Medical News Today 05 Aug 2007
After lung and stomach cancer, liver cancer is the third largest cause of cancer deaths in the world. A new study on the relationship between coffee drinking and the risk of hepatocellular carcinoma (HCC) confirmed that there is an inverse association between coffee consumption and HCC, although the reasons for this relationship are still unresolved.
The results of this study appear in the August 2007 issue of Hepatology, the official journal of the American Association for the Study of Liver Diseases (AASLD). Published by John Wiley & Sons, Inc.,
At least eleven studies conducted in southern Europe and Japan have examined the relationship between coffee drinking and the risk of primary liver cancer. The current study, led by Francesca Bravi of the Istituto di Ricerche Farmacologiche Mario Negri in Milan, Italy, was a meta-analysis of published studies on HCC that included how much coffee patients had consumed. Researchers combined all published data to obtain an overall quantitative estimate of the association between coffee consumption and HCC.
The results showed a 41 percent reduction of HCC risk among coffee drinkers compared to those who never drank coffee. "Moreover, the apparent favorable effect of coffee drinking was found both in studies from southern Europe, where coffee is widely consumed, and from Japan, where coffee consumption is less frequent, and in subjects with chronic liver diseases," the researchers state.
They point out that animal and laboratory studies have indicated that certain compounds found in coffee may act as blocking agents by reacting with enzymes involved in carcinogenic detoxification. Other components, including caffeine, have been shown to have favorable effects on liver enzymes. Coffee has also been related to a reduced risk of liver diseases and cirrhosis, which can lead to liver cancer.
"Despite the consistency of these results, it is difficult to derive a causal inference on the basis of the observational studies alone," the authors note. It may be that patients with digestive tract diseases, including liver disorders, naturally reduce their coffee consumption, even though avoidance of coffee is not routinely recommended. Also, they note that the assessment of coffee intake was based on patients' self-reporting, although recall of coffee drinking has been shown to be accurate. The fact that the inverse relationship between coffee drinking and HCC was shown in both southern Europe and Japan suggests a lack of bias in these studies. Allowance for other confounding factors, such as hepatitis B and C, cirrhosis, social class indicators, alcohol use and smoking, also suggests that such factors did not influence the results.
"In conclusion, the results from this meta-analysis provide quantitative evidence of an inverse relation between coffee drinking and liver cancer," the authors state. "The interpretation of this association remains, however, unclear and the consequent inference on causality and worldwide public health implications is still open for discussion."
Article adapted by Medical News Today from original press release.
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Coffee drinking and hepatocellular carcinoma risk: A meta-analysis
Abstract
Several studies suggest an inverse relation between coffee drinking and risk of hepatocellular carcinoma (HCC). We conducted a meta-analysis of published studies on HCC that included quantitative information on coffee consumption. Ten studies were retrieved (2,260 HCC cases), including 6 case-control studies from southern Europe and Japan (1551 cases) and 4 cohort studies from Japan (709 cases). The summary relative risk (RR) for coffee drinkers versus non-drinkers was 0.54 (95% confidence interval [CI] 0.38-0.76) for case-control studies and 0.64 (95% CI 0.56-0.74) for cohort studies. The overall RR was 0.59 (95% CI 0.49-0.72), with significant heterogeneity between studies. The overall summary RR for low or moderate coffee drinkers was 0.70 (95% CI 0.57-0.85), and that for high drinkers was 0.45 (95% CI 0.38-0.53). The summary RR for an increase of 1 cup of coffee per day was 0.77 (95% CI 0.72-0.83) from case-control studies, 0.75 (95% CI 0.65-0.85) from cohort studies, and 0.77 (95% CI 0.72-0.82) overall. The consistency of an inverse relation between coffee drinking and HCC across study design and geographic areas weighs against a major role of bias or confounding. Coffee drinking has also been related to reduced risk of other liver diseases, thus suggesting a continuum of the favorable effect of coffee on liver function. However, subjects with liver conditions may selectively reduce their coffee consumption.
Conclusion: The present analysis provides evidence that the inverse relation between coffee and HCC is real, though inference on causality remains open to discussion. (HEPATOLOGY 2007.)
Francesca Bravi 1 *, Cristina Bosetti 1, Alessandra Tavani 1, Vincenzo Bagnardi 2, Silvano Gallus 1, Eva Negri 1, Silvia Franceschi 3, Carlo La Vecchia 1 4
1 Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy
2 Dipartimento di Statistica, Università degli Studi di Milano-Bicocca, Milan, Italy
3 International Agency for Research on Cancer, Lyon, France
4 Istituto di Statistica Medica e Biometria, Università degli Studi di Milano, Milan, Italy
email: Francesca Bravi (bravi@marionegri.it) *Correspondence to Francesca Bravi, Laboratorio di Epidemiologia, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62-20157 Milan, Italy
Potential conflict of interest: Nothing to report.Funded by:
Italian Association for Cancer Research
Italian League Against Cancer
Italian Ministry of Research (PRIN 2005)
Francesca Bravi is a Fellow of the Rosario Samanin Fund
