Coffee consumption by type and risk of digestive cancer: a large prospective cohort study

BACKGROUND: Inverse associations have been observed between coffee consumption and liver cancer, but associations for other digestive cancers are unclear. Few previous studies have investigated coffee type (specifically instant or ground coffee) or a range of digestive cancer types within one cohort. We therefore investigated coffee consumption by type and digestive cancer risks in a population-based cohort. METHODS: The UK Biobank captured self-reported coffee consumption and cancer-registry recorded incident digestive cancers. Hazard ratios (HRs) and 95% CIs were calculated using Cox regression. The risk of every type of digestive cancer was investigated in association with coffee consumption by dose-response and by coffee type (decaffeinated, instant and ground). RESULTS: Over 7.5 years of follow-up, 3567 developed digestive cancer among 471,779 participants. There were 88 cases of hepatocellular carcinoma and a marked association was observed for hepatocellular carcinoma in coffee drinkers (HR 0.50, 95% CI 0.29, 0.87), which was similar for instant (HR 0.51, 95% CI 0.28, 0.93) and ground coffee (HR 0.47, 95% CI 0.20, 1.08). We did not observe significant consistently reduced risks of other individual digestive cancers amongst coffee drinkers. CONCLUSIONS: We found some evidence that coffee consumption was inversely associated with hepatocellular carcinoma which was similar by coffee type.