Tea drinking habits and oesophageal cancer in a high risk area in northern Iran: population based case-control study

doi:10.1136/bmj.b929

Published 26 March 2009, doi:10.1136/bmj.b929
Cite this as: BMJ 2009;338:b929

Research

Tea drinking habits and oesophageal cancer in a high risk area in northern Iran: population based case-control study

Farhad Islami, research fellow¹^,2^,3, Akram Pourshams, associate professor¹, Dariush Nasrollahzadeh, PhD student¹^,4, Farin Kamangar, research fellow⁵, Saman Fahimi, PhD student¹^,6, Ramin Shakeri, research fellow¹, Behnoush Abedi-Ardekani, pathologist¹, Shahin Merat, associate professor¹, Homayoon Vahedi, associate professor¹, Shahryar Semnani, associate professor and director⁷, Christian C Abnet, investigator⁵, Paul Brennan, group head², Henrik Møller, professor and director³, Farrokh Saidi, professor¹, Sanford M Dawsey, senior investigator⁵, Reza Malekzadeh, professor and director¹, Paolo Boffetta, group head and cluster coordinator²

¹ Digestive Disease Research Center, Shariati Hospital, Tehran University of Medical Sciences, 14117 Tehran, Iran, ² International Agency for Research on Cancer, Lyon, France, ³ King’s College London, Thames Cancer Registry, London, ⁴ Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden, ⁵ Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA, ⁶ Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge, ⁷ Golestan Research Center of Gastroenterology and Hepatology, Gorgan University of Medical Sciences, Gorgan, Iran

Correspondence to: R Malekzadeh malek{at}ams.ac.ir or P Boffetta boffetta{at}iarc.fr

Objective To investigate the association between tea drinkinghabits in Golestan province, northern Iran, and risk of oesophagealsquamous cell carcinoma.

Design Population based case-control study. In addition, patternsof tea drinking and temperature at which tea was drunk weremeasured among healthy participants in a cohort study.

Setting Golestan province, northern Iran, an area with a highincidence of oesophageal squamous cell carcinoma.

Participants 300 histologically proved cases of oesophagealsquamous cell carcinoma and 571 matched neighbourhood controlsin the case-control study and 48 582 participants in the cohortstudy.

Main outcome measure Odds ratio of oesophageal squamous cellcarcinoma associated with drinking hot tea.

Results Nearly all (98%) of the cohort participants drank blacktea regularly, with a mean volume consumed of over one litrea day. 39.0% of participants drank their tea at temperaturesless than 60°C, 38.9% at 60-64°C, and 22.0% at 65°Cor higher. A moderate agreement was found between reported teadrinking temperature and actual temperature measurements (weighted ${kappa}$ 0.49). The results of the case-control study showed that comparedwith drinking lukewarm or warm tea, drinking hot tea (odds ratio2.07, 95% confidence interval 1.28 to 3.35) or very hot tea(8.16, 3.93 to 16.9) was associated with an increased risk ofoesophageal cancer. Likewise, compared with drinking tea fouror more minutes after being poured, drinking tea 2-3 minutesafter pouring (2.49, 1.62 to 3.83) or less than two minutesafter pouring (5.41, 2.63 to 11.1) was associated with a significantlyincreased risk. A strong agreement was found between responsesto the questions on temperature at which tea was drunk and intervalfrom tea being poured to being drunk (weighted ${kappa}$ 0.68).

Conclusion Drinking hot tea, a habit common in Golestan province,was strongly associated with a higher risk of oesophageal cancer.

Click on image to view video

Reza Malekzadeh and other authors of this population based case-control study talk about the effect of tea drinking and oesophageal cancer in Golestan province, northern Iran

© Islami et al 2009
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Rapid Responses:

Read all Rapid Responses

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