Introduction
Methods
Search strategy and inclusion criteria
Data extraction
Study, year | Country | Study design | Participants (cases) | Age (years) | Outcome | Exposure and category | RR (95% CI) | Adjustment for covariates |
---|---|---|---|---|---|---|---|---|
Baglietto et al. 2011 | Australia | Cohort | 39,766 (67) | 27–81 | Brain glioma | Coffee: 4 cups/day or more vs. < 1cup /day | 0.51 (0.20–1.13) | Adjusted for sex, country of birth, total energy intake from diet, and level of education. |
Burch et al. 1987 | Canada | HBCC | 475 (247) | 25–80 | Brain cancer | Coffee: ever vs. never Tea: ever vs. never | Coffee: 1.26 (0.76–2.09) Tea: 1.13 (0.73–1.72) | Adjusted for age, sex, area of residence, marital status, and date of diagnosis or death. |
Dubrow et al. 2012 | USA | Cohort | 545,771 (904) | 50–71 | Brain glioma | Coffee: ≥6 cups/day vs. none Tea: > 3 cup/day vs. none Tea plus coffee: > 5 cup/day vs. none | Coffee: 1.04 (0.70–1.55) Tea: 0.75 (0.57–1.00) Tea plus coffee: 0.68 (0.46–1.03) | Adjusted for age, sex, race/ethnicity, height, and intake of total energy, fruit, vegetable, and nitrites. |
Efird et al. 2004 | USA | Cohort | 133,811 (130) | ≥ 25 | Brain glioma | Coffee: ≥ 7 cups/day vs. < 1 cup/day | 1.7 (0.8–3.6) | Adjusted for age, sex, race, smoking, education, and alcohol. |
Hashibe et al. 2015 | USA | Cohort | 97,334 (103) | 55–74 | Brain glioma | Coffee: ≥ 2 cups/day vs. < 1 cup/day Tea: ≥ 1 cup/day vs. < 1 cup/day | Coffee: 0.76 (0.50–1.17) Tea: 1.04 (0.65–1.66) | Adjusted for age (continuous), sex, race, and education. |
Hochberg et al. 1990 | USA | PBCC | 288 (160) | 15–81 | Brain glioma | Coffee: ≥ 4 cups/day vs. < 1 cup/day | 0.9 (0.5–1.8) | Adjusted for age, sex, and socio-economic status. |
Holick et al. 2010 | USA | Cohort | 230,655 (335) | 25–75 | Brain glioma | Coffee: ≥ 4 cups/day vs. none Tea: ≥ 8 cups/day vs. none Tea plus coffee: ≥ 5 cups/ day vs. < 1 cup/day | Coffee: 0.80 (0.54–1.17) Tea: 0.71 (0.45–1.12) Tea plus coffee: 0.60 (0.41–0.87) | Adjusted for age, sex, total caloric intake. (Further adjustments for cigarette smoking, current smoking, intake of processed meat, alcohol, fruit and vegetables , and, for women, reproductive factors did not change the risk estimates) |
Malmir et al. 2017 | Iran | HBCC | 384 (128) | 43.4 ± 14.6 | Brain glioma | Coffee: T3 vs. T1 Tea: T3 vs. T1 Tea plus coffee: T3 vs. T1 | Coffee: 0.09 (0.03–0.24) Tea: 0.33 (0.13–0.86) Tea plus coffee: 0.35 (0.15–0.83) | Adjusted for energy intake, physical activity, family history of cancers, family history of glioma, marital status, education, highrisk occupation, high-risk residential area, duration of cell phone use, supplement use, history of exposure to the radiographic X-ray, history of head trauma, history of allergy, history of hypertension, smoking status, exposure to chemicals, drug use, personal hair dye, frequent fried food intake, frequent use of barbecue, canned foods and microwave, meats and processed meats, legumes and nuts, fruits, salt and interaction effects of tea and coffee consumption, and BMI. |
Michaud et al. 2010 | France, Italy, Spain, Denmark, Germany, Greece, Netherlands, Norway, Sweden, UK | Cohort | 521,448 (343) | 25–70 | Brain glioma | Coffee: Q5 vs. Q1 Tea: Q4 vs. Q1 Tea plus coffee: Q5 vs. Q1 | Coffee: 0.98 (0.67–1.41) Tea: 1.05 (0.75–1.48) Tea plus coffee: 1.02 (0.72–1.44) | Adjusted for age, sex, country, body mass index, smoking status, and education. |
Nelson et al. 2012 | USA | Cohort | 8006 (9) | 45–68 | Brain glioma | Coffee: ≥ 4 cups/day vs. none Tea: ≥ 4 cups/day vs. none | Coffee: 0.89 (0.08–10.02) Tea: 1.21 (0.22–6.76) | Adjusted for age, education, and triceps skinfold thickness |
Ogawa et al. 2016 | Japan | Cohort | 106,324 (157) | 40–69 | Brain cancer Brain glioma | Coffee: ≥ 3 cups/day vs. ≤ 4 days/week Tea: ≥ 3 cups/day vs. ≤ 4 days/week | Brain cancer: Coffee: 0.48 (0.23–1.00) Tea: 0.55 (0.17–1.84) Brain glioma: Coffee: 1.07 (0.70–1.62) Tea: 1.05 (0.54–2.05) | Adjusted for age, sex, BMI, pack-years of cigarettes (never and past, 0–20, > 20), alcohol intake (non and past and 1–3 times/month, drinker ≤ 150, 150 g of ethanol per week), green tea (≤ 4 days/week, 1–2 cups/day, ≥ 3 cups/day), and past history of allergy, past history of diabetes mellitus. |
Statistical analysis
Results
Study selection and study characterization
Coffee consumption and the risk of brain cancer
Subgroups | Tea consumption (highest vs. lowest category) | Coffee consumption (highest vs. lowest category) | ||||||
---|---|---|---|---|---|---|---|---|
Studies, n | RR (95% CI) | I2 (%) |
P
heterogeneity
| Studies, n | RR (95% CI) | I2 (%) |
P
heterogeneity
| |
All studies | 8 | 0.897 (0.739–1.088) | 29.9 | 0.189 | 11 | 0.785 (0.580–0.984) | 65.6 | 0.001 |
Glioma | 7 | 0.846 (0.683–1.047) | 24.6 | 0.241 | 10 | 0.760 (0.548–0.972) | 63.9 | 0.003 |
Cohort | 6 | 0.891 (0.755–1.051) | 0.0 | 0.471 | 8 | 0.858 (0.700–0.992) | 20.1 | 0.270 |
Case-control | 2 | 0.658 (0.199–2.179) | 81.5 | 0.020 | 3 | 0.507 (0.142–1.810) | 90.1 | < 0.001 |
America | 4 | 0.798 (0.646–0.986) | 0.0 | 0.595 | 6 | 0.912 (0.740–1.124) | 0.0 | 0.520 |
Europe | 2 | 1.080 (0.828–1.410) | 0.0 | 0.792 | 2 | 1.070 (0.793–1.444) | 0.0 | 0.433 |
Asia | 2 | 0.643 (0.205–2.016) | 79.9 | 0.026 | 2 | 0.217 (0.042–0.896) | 84.9 | 0.010 |
Oceania | – | – | – | – | 1 | – | – | – |