Consumption of Coffee Associated With Reduced Risk of Liver Cancer

A Meta-Analysis

Li-Xuan Sang; Bing Chang; Xiao-Hang Li; Min Jiang

Disclosures

BMC Gastroenterol. 2013;13(34) 

In This Article

Results

Study Characteristics

Figure 1 shows the process of selecting studies for the meta-analysis. Sixteen observational articles examining the association between coffee consumption and the risk of liver cancer were included in our meta-analysis (Table 3).[11–25] There were nine case–control studies[11–19] and seven cohort studies (two of these were nested in a cohort article).[20–25] Of the selected studies, 11 were conducted in Asia (nine in Japan,[14,15,17,18,20–22,24] one in Singapore,[25] one in Hong Kong[19]) and five in Europe (one in Finland,[23] two in Italy,[13,16] one in Greece,[11] one in Italy and Greece[12]). Among case–control studies, seven were hospital-based case–control studies,[11–16,19] and two were nested case- control studies.[17,18]

Figure 1.

Process of study selection in the meta-analysis.

High vs Non/Almost Never Drinkers

A meta-analysis of risk estimates for the incidence of liver cancer for highest compared with lowest coffee consumption categories could be conducted with data from nine case–control studies and nine cohort studies. Our results showed a 50% reduction in risk of liver cancer with the highest intake of coffee (summary OR: 0.50, 95%CI: 0.42–0.59) (Figure 2). There was no significant heterogeneity across studies (Q = 16.71, P = 0.337, I2 = 10.2%). There was a symmetric funnel plot and no evidence of significant publication bias from Egger's test (P = 0.05) and Begg's test (P = 0.096) (Figure 3).

Figure 2.

Risk estimates from studies assessing the association between high coffee consumption (highest versus non/occasionally) and liver cancer risk.

Figure 3.

Begg's funnel plot of coffee consumption and risk of liver cancer.

A sensitivity analysis for the risk of liver cancer was performed by excluding one study,[22] the outcome of which was mortality. The summary OR was 0.49 (95%CI: 0.41–0.59). There was no significant heterogeneity across studies (Q = 16.7, P = 0.272, I2 = 16.2%).

Similar results were found in a subgroup analyses conducted by study design in case–control studies (OR: 0.50, 95%CI: 0.40–0.63, Q = 12.38, P = 0.125, I2 = 36.8%), and cohort studies (OR: 0.48, 95% CI: 0.38–0.62, Q = 2.47, P = 0.676, I2 = 0.0%) (Figure 4).

Figure 4.

Forest plot of coffee consumption and risk of liver cancer, stratified by study type.

In a subgroup analysis conducted by sex, only four studies were included in the analysis: studies in males gave an OR of 0.38 (95% CI: 0.25–0.56, Q = 1.83, P = 0.609, I2 = 0.0%), while studies in females gave an OR of 0.60 (95% CI: 0.33–1.10, Q = 0.94, P = 0.815, I2 = 0.0%) (Table 4).

When stratified analysis was conducted by study region, a statistically significant protective effect of coffee consumption on liver cancer was observed in Asia (OR: 0.45, 95% CI: 0.36–0.56, Q = 7.86, P = 0.642, I2 = 0.0%), and in Europe (OR: 0.57, 95% CI: 0.44–0.75, Q = 7.09, P = 0.131, I2 = 43.6%) (Figure 5).

Figure 5.

Forest plot of coffee consumption and risk of liver cancer, stratified by study region.

Stratification analysis was conducted without or with adjustment for a history of liver disease. A statistically significant protective effect of coffee consumption on liver cancer was observed with no adjustment for a history of liver disease (OR: 0.39, 95% CI: 0.28–0.54, Q = 5.34, P = 0.254, I2 = 25.1%) and after adjustment for a history of liver disease (OR: 0.54, 95% CI: 0.46–0.66, Q = 8.5, P = 0.581, I2 = 0.0%).

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