green tea consumption is associated with a ... - congress · green tea consumption is associated...

www.worldcancercongress.org

Disclosure of Interest: None Declared Abstract code:

Green Tea Consumption Is Associated with a Reduced Risk of Adult Leukaemia

Authors: Ping Liu, C D’Arcy J Holman, Jie Jin, Min Zhang

School of Population Health, The University of Western Australia

332

Oolong tea 8-20%

Black tea 3-10%

Green tea 30-42%

China, Japan, Africa & Middle East

≈ 20%

Southern China & Taiwan ≈ 2%

Western countries ≈ 78%

Tealeaves (Camellia sinensis)

Processing

Semi-fermented

Tea Type (Catechins, % dry weight)

BACKGROUND Tea

Ping Liu Melbourne, 5 December 2014

Reference: Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med 1992;21:334-50.

Where consumed

Unfermented

Fermented

% tea products worldwide

BACKGROUND & AIMS Epidemiologic studies on tea consumption and leukaemia risk


Study ID Study Design Population Participants OR/RR (95%CI)

Li 2006

Hospital-based case-control American 111 AML cases

439 controls Males 0.3 (0.1-0.8)

Females 0.5 (0.2-1.1)

Ma 2010 Cohort American 338 AML cases

491,163 cohorts 0.9 (0.6-1.2)

Kabat 2013 Cohort American 178 CML cases

493,188 cohorts 1.0 (0.7–1.4)

Zhang 2008

Hospital-based case-control Chinese 107 leukaemia cases

110 controls 0.4 (0.2-0.9)

Kuo 2009

Population-based case-control Taiwanese

252 leukaemia cases (159 children/93 adults)

637 controls

Adults 0.5 (0.2-0.9) Children 0.6 (0.2-1.8)

METHODS Study sites


Hangzhou

Shenyang

METHODS Participants Ø  493 incident cases: Diagnosed as de-novo adult leukaemia Ø  493 hospital-based controls: Free of caners at the time of recruitment Recruited from outpatients Matching cases’ gender, age, and study site

Ø  Face-to-face interview

Ø  Types of tea

Ø  Duration of consumption

Ø  Frequency of consumption

Ø  Amount consumed


Tea consumption ascertainment

METHODS Other information collected Ø  Demographics

Ø  Lifestyle: smoking, alcohol drinking and physical activity

Ø  Foods consumption: 103−item Food Frequency Questionnaire

Ø  Family history of cancer

Ø  Conditional logistic regression: ORs (95% CIs)

Ø  Adjustments: potential confounders (demographic, lifestyle and dietary factors)


Statistical analysis

RESULTS Selected characteristics of participants


Characteristics Cases (n=493) Controls (n=493) Age at interview (yrs) 45.2±15.3 45.1±15.1 Male 289 (58.6) 289 (58.6) Residential location (Rural) 106 (21.5) 87 (17.6) Education (Tertiary)* 87 (17.6) 204 (41.4) Body mass index (≥25 kg/m²) 77 (15.6) 99 (20.1) Physical activity (MET hrs/wk) 83.7±87.6 76.1±74.1 Cigarette smoking* 178 (36.1) 149 (30.2) Alcohol drinking 281 (57.0) 274 (55.6) Coffee consumption* 81 (16.4) 124 (25.2) Vegetables intake (g/d)* 239.8±169.6 282.2±158.8 Fruits intake (g/d)* 109.9±115.6 178.6±166.9 Energy intake (kcal/d)* 2909.5±1251.5 2753.4±918.8

Cancer history in first degree relatives 49 (9.9) 49 (9.9)

* p<0.05. Categorical variables expressed as n(%); Continuous variables: mean ± SD

RESULTS Tea consumption between cases and controls


Cases (n=493,%) Controls (n=493,%)

RESULTS Adjusted ORs and 95% CIs for green tea consumption


0

0.2

0.4

0.6

0.8

1

Adj

uste

d O

R

Non-tea drinkers

Yes

All (n=806)

Men (n=471)

Women (n=335)

Yes Yes Non-tea drinkers

Non-tea drinkers

RESULTS Adjusted ORs and 95% CIs for duration of drinking (yrs)


Adj

uste

d O

R

All (n=804)

Men (n=469)

Women (n=335)

P (trend)=0.03 P (trend)<0.001 P (trend)<0.001

0

0.2

0.4

0.6

0.8

1

0 <15 >15−<30 ≥30 0 <15 >15−<30 ≥30 0 <15 >15−<30 ≥30

P (trend)<0.001

RESULTS Adjusted ORs and 95% CIs for No. of cups daily


Adj

uste

d O

R

All (n=806)

Men (n=471)

Women (n=335)

0

0.2

0.4

0.6

0.8

1

0 <1 1 ≥2 0 <1 1 ≥2 0 <1 1 ≥2 P (trend)<0.001 P (trend)=0.001

RESULTS Adjusted ORs and 95% CIs for dried tealeaves (kg/yr)


Adj

uste

d O

R

All (n=804)

Men (n=469)

Women (n=335)

0

0.2

0.4

0.6

0.8

1

0 ≤0.5 >0.5−≤1 >1 0 ≤0.5 >0.5−≤1 >1 0 ≤0.5 >0.5−≤1 >1

P (trend)<0.001 P (trend)<0.001 P (trend)=0.02

RESULTS Subgroup analysis

Ø Significant inverse dose-response relationship between green tea consumption and risk of AML was observed across all the measures.

Ø Could not analyse the associations on ALL, CML and CLL, due to small number of patients.


DISCUSSION Potential Bias


Bias?

Recall bias?

Influence by mass media?

Influence by disease status?

Hospital-based case-control

design

Reference: Li L, Zhang M, Holman D. Population versus hospital controls for case-control studies on cancers in Chinese hospitals. BMC Med Res Methodol 2011;11:167.

DISCUSSION Strengths

Ø Multi-centre study Ø Moderate sample size Ø Face-to-face interview Ø Validated questionnaire Ø High response (98% in cases vs. 92% in controls)


CONCLUSIONS

Ø  Regular daily consumption of green tea can

protect against adult leukaemia.

Ø  Green tea drinking, a modifiable dietary preventive

factor, may shed ‘green light’ in the primary

prevention of adult leukaemia.


ACKNOWLEDGEMENTS

¡  The authors acknowledge with gratitude the participation of participants.

¡  The authors are grateful for the collaboration received from three participating hospitals and their staff for their kind assistance in fieldwork.

¡  The work was supported by the National Health and Medical Research Council (Australia) Project Grant (572542).

¡  The presenter is supported by UWA Scholarships for International Research Fees, University Postgraduate Award for International Student, and Safety-Net Top-up Scholarship.


THANK YOU!


green tea consumption is associated with a ... - congress · green tea consumption is associated...

Documents