Green tea consumption is associated with a reduced risk of adult leukemia

Background: Tea polyphenols have consistently demonstrated leukemic-inhibition in numerous vivo and vitro studies. However, epidemiologic studies on the association between tea consumption and adult leukemia risk are limited and inconclusive. Aim: A case-control study conducted in China between 2008 and 2012 to investigate the association between tea consumption and adult leukemia risk. Methods: This included 493 incident, hematologically confirmed leukemia cases and 493 outpatient controls matched to each case by gender, year-of-birth quinquennium, and study site. Information on type, duration, frequency, and quantity of tea consumption, diet, lifestyle, and demographic characteristics was collected by face-to-face interview using a reliable structured questionnaire. Odds ratios (ORs) were estimated using conditional logistic regression after adjusted for resident locality, education, tobacco smoking, alcohol consumption, and fruits intake. Results: Among cases with leukemia subtype information (414 out of 493), 67.6% were acute myeloid leukemia, 16.9% acute lymphoblastic leukemia, 10.4% chronic myeloid leukemia, and 5.1% chronic lymphocytic leukemia. There were 49.5% of the cases who drank tea compared with 65.9% of the controls. Among tea drinkers, 95.8% reported drinking green tea only or green tea with black or oolong tea. Compared with non-tea drinkers, the adjusted ORs (95% confidence intervals) were 0.30 (0.17-0.54), 0.26 (0.16-0.42), and 0.28 (0.17-0.47) for those who consumed tea ≥30 years, ≥2 cups daily, and dried tealeaves >1000g annually, respectively. A significant inverse relationship was observed across all tea measurements with a statistically significant test for trend (P <0.001). In analysis of leukaemia subtype, higher tea consumption was associated with a lower risk of acute myeloid leukaemia. The inverse association existed in both males and females after stratification, and a greater risk reduction was observed in females. Conclusions: We conclude that regular daily consumption of green tea can protect against adult leukemia.