Boiled coffee consumption and the risk of prostate cancer: follow-up of 224,234 Norwegian men 20–69 years

BACKGROUND: There is insufficient epidemiological evidence on the relationship between type of coffee and the risk of prostate cancer. METHODS: The risk of prostate cancer by use of boiled vs not boiled coffee were assessed in a prospective study of 224,234 men 20–69 years. 5740 incident prostate cancers were identified. RESULTS: With no coffee as reference group the hazard ratios of <1–4, 5–8 and 9+ cups per day of boiled coffee only were 0.84 (0.73–0.96), 0.80 (0.70–0.92) and 0.66 (0.55–0.80), P-trend=0.00. The corresponding figures for not boiled coffee were 0.89 (0.80–0.99), 0.91 (0.81–1.02) and 0.86 (0.74–1.00), P-trend=0.22. CONCLUSION: An inverse relationship between number of cups per day and the risk of prostate cancer was present only for the boiled coffee type.