Coffee drinking and hepatocellular carcinoma risk

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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.)