Background
Methods
Search strategy
Inclusion criteria
Data extraction
Statistical analysis
Results
Characteristics of included studies
Study | Country; design | Study period | Population | Green tea intake levels OR or RR (95% CI) | Adjustments |
---|---|---|---|---|---|
Gao (1994) | Shanghai China population-based, hostipal-control study | 1990-1993 | 902 (male:622, female: 280) cases and 1552 (male:854, female: 698) hospital-based controls | Male: drinking vs. never drinking 0.80 (0.58-1.09) 1-199g/month vs. never drinking 0.79 (0.53-1.17) >200g/month vs. never drinking 0.79 (0.56-1.13) Female: drinking vs. never drinking 0.50 (0.30-0.83) 1-199g/month vs. never drinking 0.77 (0.39-1.53) >150g/month vs. never drinking 0.34 (0.17-0.69) | Age, education, birthplace, cigarette smoking (both sexes), and alcohol intake (men only). |
Yang (1999) | Yangzhong China population-based, case control study | 1998-1998 | 68 cases and 68 population- based controls | drinking vs. never drinking 0.20 (0.06- 0.67) | Age, education, cigarette smoking, and alcohol intake . |
Mu (2003) | Taixing, China population-based, case control study | 2000-2000 | 218 cases and 415 hospital based controls | <125g/month vs. never drinking 1.13 (0.67-1.92) 125-250g/month vs. never drinking 0.78 (0.46-1.34) >250g/month vs. never drinking 0.58 (0.35-0.97) | Age, education, cigarette smoking, and alcohol intake . |
Astunobu,cohort 1 (2006) | Japan prospective cohort study | 9 years | 38 cases among 9008 residents in Miyagi prefecture | 1-2 cups/day vs. < never or occasionally 0.69(0.17-2.91) 3–4 cups/day vs. < never or occasionally 1.58(0.52-4.76) 5 cups/day vs. < never or occasionally 1.78(0.66-4.82) | Age, sex, cigarette smoking, alcohol consumption, consumption of black tea, coffee |
Astunobu,cohort 2 (2006) | Japan prospective cohort s tudy | 7.6 years | 40 cases among 17715 residents in Miyagi prefecture | 1-2 cups/day vs. < never or occasionally 1.22 (0.47-3.19) 3–4 cups/day vs. < never or occasionally 0.85 (0.30-2.40) 5 cups/day vs. < never or occasionally 1.61(0.71-3.66) | Age, sex, cigarette smoking, alcohol consumption, consumption of black tea, coffee |
Wang (2007) | China population based case control study | 2004-2006 | 355(male:223, female: 132) cases and 408 (male:252, female: 156) population controls | Male: drinking vs. never drinking 1.37 (0.95–1.98) Female: drinking vs. never drinking 0.26 (0.07–0.94) | Age (continuous), , sex, cancer family history and BMI, marital status and education years. smoking , alcohol drinking. |
Wu (2009) | Dafeng China population based case control study | 2003-2007 | 637(male:426, female: 211) cases and 1938 (male:1368, female: 570) Dafeng population controls | <150g/month vs. never drinking 1.0 (0.7-1.3) 125-250g/month vs. never drinking 1.0 (0.6-1.8) >250g/month vs. never drinking 1.0 (0.6–2.0) | Age , gender, education level, income, cancer family history, BMI smoking , alcohol drinking. tea temperature |
Wu (2009) | Ganyu China population based case control study | 2003-2007 | 883 (male:765, female: 118) cases and 1941 (male:1548, female: 393) Gany population controls | <150g/month vs. never drinking 1.1(0.7-1.7) 125-250g/month vs. never drinking 1.0 (0.7-1.6) >250g/month vs. never drinking 1.6 (1.1–2.2) | age , gender, education level, income, cancer family history, BMI smoking , alcohol drinking. tea temperature |
Chen (2011) | Guangdong China hospital based case control study | 2004-2010 | 150 cases and 300 hospital based controls | <100g/month vs. never drinking 1.27(0.72-1.89) 100-250g/month vs. never drinking 0.97 (0.59-2.56) >250g/month vs. never drinking0.92 (0.49-2.32) | age, sex, education level, annual income, cancer family history, smoking and drinking status |
Islami (2009) | Northern Iran population based case control study | 2003-2007 | 266 cases and 386 population- based controls | Daily, weekly vs Never, <weekly 0.65 (0.32 to 1.31) | ethnicity, daily vegetable intake alcohol consumption, tobacco or opium ever use, duration of residence in rural areas, |
Meta-Analysis of categories of consumption
No. of studies | No. of cases | RR or OR (95% CI) | Heterogeneity | Publication bias | |||
---|---|---|---|---|---|---|---|
p | I2
| Begg’s test | Egger’s test | ||||
Overall
| 10 | 3557 | 0.76(0.49-1.02) | 0.00 | 0.73 | 0.37 | 0.16 |
Country
| |||||||
Japan | 2 | 78 | 1.67(0.46-2.87) | 0.90 | 0.00 | 1.00 | NA |
China | 7 | 3213 | 0.73(0.44-1.02) | 0.00 | 0.79 | 0.12 | 0.05 |
Northern Iran | 1 | 266 | 0.65 (0.32-1.31) | NA | NA | NA | NA |
Study design
| |||||||
Cohort studies | 2 | 78 | 1.67(0.46-2.87) | 0.90 | 0.00 | 1.00 | NA |
Case control | 8 | 3479 | 0.72(0.45-0.98) | 0.00 | 0.76 | 0.07 | 0.02 |
Participates source
| |||||||
PCC | 7 | 3329 | 0.71 (0.43-0.98) | 0.00 | 0.78 | 0.05 | 0.02 |
HCC | 1 | 150 | 0.92 (0.49-2.32) | NA | NA | NA | NA |
Gender
| |||||||
Male | 2 | 845 | 1.04(0.48-1.60) | 0.05 | 0.73 | 1.00 | NA |
Female | 2 | 412 | 0.32(0.10-0.54) | 0.75 | 0.00 | 1.00 | NA |
No. of studies | No. of cases | RR or OR (95% CI) | Heterogeneity | Publication bias | |||
---|---|---|---|---|---|---|---|
p | I2
| Begg’s test | Egger’s test | ||||
Overall
| 10 | 3557 | 0.86(0.70-1.03) | 0.00 | 0.56 | 0.24 | 0.22 |
Country
| |||||||
Japan | 2 | 78 | 1.14(0.46-2.87) | 0.90 | 0.00 | 0.26 | 0.17 |
China | 7 | 3213 | 0.86 (0.67-1.05) | 0.00 | 0.67 | 0.04 | 0.03 |
Northern Iran | 1 | 266 | 0.65 (0.32-1.31) | NA | NA | NA | NA |
Study design
| |||||||
Cohort studies | 2 | 78 | 1.14(0.46-2.87) | 0.90 | 0.00 | 0.26 | 0.17 |
Case control | 8 | 3479 | 0.85(0.67-1.02) | 0.00 | 0.65 | 0.03 | 0.02 |
Participates source
| |||||||
PCC | 7 | 3329 | 0.82(0.63-1.01) | 0.00 | 0.69 | 0.03 | 0.01 |
HCC | 1 | 150 | 1.13(0.69-1.57) | 0.77 | 0.00 | 0.30 | 0.01 |
Gender
| |||||||
Male | 2 | 845 | 1.04(0.49-1.59) | 0.05 | 0.74 | 1.00 | NA |
Female | 2 | 412 | 0.43(0.21-0.66) | 0.35 | 0.00 | 1.00 | NA |
No. of studies | No. of cases | RR or OR (95% CI) | Heterogeneity | Publication bias | |||
---|---|---|---|---|---|---|---|
p | I2
| Begg’s test | Egger’s test | ||||
Overall
| 10 | 3557 | 0.83(0.58-1.08) | 0.00 | 0.66 | 0.12 | 0.03 |
Country
| |||||||
Japan | 2 | 78 | 0.96(0.01-1.92) | 0.59 | 0.00 | 1.00 | NA |
China | 7 | 3213 | 0.85(0.56-1.13) | 0.00 | 0.75 | 0.18 | 0.03 |
Northern Iran | 1 | 266 | 0.65 (0.32-1.31) | NA | NA | NA | NA |
Study design
| |||||||
Cohort studies | 2 | 78 | 0.96 (0.01-1.92) | 0.59 | 0.00 | 1.00 | NA |
Case control | 8 | 3479 | 0.82 (0.56-1.09) | 0.00 | 0.72 | 0.07 | 0.01 |
Participates source
| |||||||
PCC | 7 | 3329 | 0.78(0.51-1.05) | 0.00 | 0.73 | 0.03 | 0.01 |
HCC | 1 | 150 | 1.27(0.72-1.89) | NA | NA | NA | NA |
Gender
| |||||||
Male | 2 | 845 | 1.04(0.48-1.61) | 0.06 | 0.72 | 1.00 | NA |
Female | 2 | 412 | 0.45(0.10-0.79) | 0.16 | 0.49 | 1.00 | NA |