A Prospective Study of Green Tea Consumption and Oral Cancer Incidence in Japan

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Annals of Epidemiology
Volume 17, Issue 10, October 2007, Pages 821-826

A Prospective Study of Green Tea Consumption and Oral Cancer Incidence in Japan
Reiko Ide DDS, PhD, a, Yoshihisa Fujino MD, PhD, MPH, a, Yoshiharu Hoshiyama PhD, a, Tetsuya Mizoue MD, PhD, a, Tatsuhiko Kubo MD, PhD, a, Truong-Minh Pham MD, a, Kiyoyumi Shirane MD, a, Noritaka Tokui MD, PhD, a, Kiyomi Sakata MD, PhD, MPH, a, Akiko Tamakoshi MD, PhD, a, Takesumi Yoshimura MD, PhD, MPH, a and for the JACC Study Group*

a From the Department of Clinical Epidemiology, Institute of Industrial Ecological Sciences (R.I., K.S., N.T.), and the Department of Preventive Medicine and Community Health, School of Medicine (Y.F., T-M.P.), University of Occupational and Environmental Health, Kitakyusyu, Japan; University of Human Arts and Sciences, Saitama (Y.H.); Department of Epidemiology and International Health, Research Institute, International Medical Center of Japan, Tokyo (T.M.); Asahi Kasei, Nobeoka office Health Care Center, Miyazaki (T.K.); the Department of Hygiene and Preventive Medicine, Iwate Medical University School of Medicine, Morioka (K.S.); National Center for Geriatrics and Gerontology, Aichi (A.T.); and Fukuoka Institute of Health and Environmental Sciences Fukuoka (T.Y.), Japan

Received 20 November 2006; accepted 20 April 2007. Available online 2 July 2007.

Purpose
To examine the relation of green tea consumption with oral carcinogenesis, we prospectively analyzed data from a nationwide large-scale cohort study in Japan.

Methods
A total of 20,550 men and 29,671 women aged 40Ò79 years, without any history of oral and pharyngeal cancer at baseline survey, were included in the present study. During a mean follow-up period of 10.3 years, 37 oral cancer cases were identified. The Cox proportional hazard model was used to estimate the hazard ratio (HR) and 95% confidence interval (95% CI) for oral cancer according to green tea consumption by sex, while adjusting for age, smoking, alcohol drinking, and other dietary factors.

Results
For women, the HRs of oral cancer for green tea consumption of 1Ò2, 3Ò4, and 5 or more cups per day were 0.51 (95% CI: 0.10Ò2.68), 0.60 (95% CI: 0.17Ò2.10), and 0.31 (95% CI: 0.09Ò1.07), respectively, compared with those who drank less than one cup per day (p for trend, 0.08). For men, no such trends were observed.

Conclusions
Our findings did not suggest a prominent inverse association of green tea consumption with oral cancer, although there was a tendency for a reduced risk in women.

Key Words: Oral Cancer; Green Tea; Cohort Study

Abbreviations: CI, confidence interval; EGCG, (-)-epigallocatechin-3-gallate; HR, hazard ratio; ICD, International Classification of Disease; JACC Study, Japan Collaborative Cohort Study; SAS, Statistical Analysis System


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