Green tea consumption and risk of hematologic neoplasms : the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study)

Purpose Experimental studies suggested that green tea may have an anticancer effect on hematologic neoplasms. However, few prospective studies have been conducted. Methods A total of 65,042 individuals aged 40-79 years participated in this study and completed a self-administered questionnaire about their lifestyle and medical history at baseline (1988-1990). Of these, 52,462 individuals living in 24 communities with information on incident hematologic neoplasms available in the cancer registry, who did not have a history of cancer and provided valid information on frequency of green tea consumption, were followed through 2009. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the incidence of hematologic neoplasms according to green tea consumption were analyzed. Results The incidence of hematologic neoplasms during a median follow-up of 13.3 years was 323. Compared with the never-drinkers of green tea, the multivariate HRs and 95% CIs for total hematologic neoplasms in green tea drinkers of = 2 cups/day, 3-4 cups/day, and = 5 cups/day were 0.65 (0.42-1.00), 0.73 (0.47-1.13), and 0.63 (0.42-0.96), respectively. The association was more prominent for acute myeloid leukemias and follicular lymphomas. Conclusions The present cohort study suggests a protective effect of green tea against hematologic neoplasms, especially acute myeloid leukemias