Several
studies released over the past several years have added to the evidence that coffee
may have a beneficial effect on the liver.
As reported in the August 2007
issue of Hepatology, Italian researchers performed a meta-analysis of epidemiologic
studies to quantitatively assess the relation between coffee consumption and the
risk of liver cancer.
Relevant
studies were identified by searching MEDLINE from 1966 through February 2007,
and going through the reference lists of retrieved articles. The researchers included
cohort and case-control studies that reported relative risk estimates with 95%
confidence intervals of primary liver cancer or hepatocellular
carcinoma (HCC) by quantitative categories of coffee consumption.
Results
•
4
cohort studies (from Japan) and 5 case-control studies (from southern Europe and
Japan) met the inclusion criteria.
•
Altogether,
these studies involved 2260 cases (patients with liver cancer) and 239,146 non-cases
(control subjects).
•
All
studies observed an inverse relation between coffee consumption and risk of liver
cancer, indicating that coffee has a protective effect.
•
In
6 studies, the association was statistically significant.
•
Overall,
an increase in consumption of 2 cups of coffee per day was associated with a 43%
reduction in the risk of liver cancer (RR 0.57; 95% CI 0.49-0.67).
•
The
reduction in risk was greater (55%) for heavy coffee drinkers, and less (30%)
for low-to-moderate coffee consumers.
•
In
a stratified analysis, the summary relative risks of liver cancer for an increase
in consumption of 2 cups of coffee per day were 0.69 (95% CI 0.55-0.87) for people
without a history of liver disease and 0.56 (95% CI 0.35-0.91) for those with
past liver disease.
•
The
association between coffee consumption and liver cancer risk remained even after
adjusted for potentially confounding factors including liver cirrhosis, hepatitis
B and C, social class, alcohol intake, and smoking status.
Conclusion
In
conclusion, the authors wrote, "Findings from this meta-analysis suggest
that an increased consumption of coffee may reduce the risk of liver cancer."
However,
they cautioned, "The present analysis provides evidence that the inverse
relation between coffee and HCC is real, though inference on causality remains
open to discussion."
It
is unclear why coffee consumption is associated with lower risk of liver cancer,
but it may be related to coffee's protective effect with regard to fibrosis and
cirrhosis.
Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy;
Dipartimento di Statistica, Università degli Studi di Milano-Bicocca, Milan,
Italy; International Agency for Research on Cancer, Lyon, France; Istituto di
Statistica Medica e Biometria, Università degli Studi di Milano, Milan,
Italy.
08/31/07
Reference F
Bravi, C Bosetti, A Tavani, and others. Coffee Drinking and Hepatocellular Carcinoma
Risk: A Meta-Analysis. Hepatology 46(2): 430435. August 2007.
