Introduction
Materials and methods
Subjects
Data collection
Statistical analysis
Results
Swedish study | MARIE study | |||||||
---|---|---|---|---|---|---|---|---|
Characteristic | Breast cancer cases/controls | Cases | Controls | P
a
| Breast cancer cases/controls | Cases | Controls | P
b
|
Age (matching factor, years) | 2,818/3,111 | 63.4 ± 6.7 | 64.3 ± 6.5 | - | 2,651/5,395 | 63.2 ± 5.6 | 63.2 ± 5.5 | - |
Age at menarche (years) | 2,558/2,832 | 13.5 ± 1.4 | 13.6 ± 1.4 | 0.0565 | 2,369/4,580 | 13.6 ± 1.6 | 13.7 ± 1.7 | 0.0026 |
Age at menopause (years) | 2,803/3,093 | 50.4 ± 3.5 | 50 ± 3.9 | < 0.0001 | 1,614/3,417 | 49.5 ± 4.7 | 49.0 ± 5.0 | 0.0014 |
Parity (No. of live births) | 2,818/3,110 | 1.8 ± 1.2 | 2.1 ± 1.4 | < 0.0001 | 2,651/5,395 | 1.6 ± 1.1 | 1.7 ± 1.2 | < 0.0001 |
Age at first birth (years) | 2,373/2,753 | 25.3 ± 4.9 | 24.6 ± 4.6 | < 0.0001 | 2,185/4,537 | 24.7 ± 4.6 | 24.5 ± 4.4 | 0.1879 |
Body mass index (kg/m2) | 2,803/3,065 | 25.8 ± 4.2 | 25.5 ± 4.2 | 0.0009 | 2,651/5,390 | 23.2 ± 3.2 | 23.3 ± 3.3 | 0.7134 |
Alcohol consumption (g/day) | 2,537/2,400 | 2.5 ± 4.5 | 2.1 ± 3.9 | 0.0032 | 2,649/5,389 | 8.9 ± 18.2 | 8.4 ± 13.8 | 0.1731 |
History of breast cancer in first degree relative (Yes, %) | 2,745/2,607 | 15.6 | 7.7 | < 0.0001 | 2,512/5,096 | 18.6 | 12.6 | < 0.0001 |
History of benign breast disease (Yes, %) | 2,818/3,111 | 13.9 | 8.1 | < 0.0001 | 2,647/5,379 | 41.2 | 34.9 | < 0.0001 |
Use of hormone replacement therapy (Ever, %) | 2,811/3,087 | 48.4 | 40.3 | < 0.0001 | 2,645/5,375 | 68.5 | 60.7 | < 0.0001 |
Smoked > 1 year or > 100 cigarettes (Yes, %) | 2,817/3,109 | 42.5 | 44.3 | 0.6490 | 2,651/5,393 | 46.2 | 46.4 | 0.8602 |
Education, categorical* | 2,800/2,646 | 0.0797 | 2,649/5,395 | 0.4634 | ||||
- elementary school | 45.4 | 46.7 | ||||||
- junior secondary school | 24.8 | 21.5 | low | 56.5 | 57.2 | |||
- high school | 15.2 | 13.8 | medium | 28.4 | 28.7 | |||
- university | 13.9 | 12.0 | high | 15.1 | 14.1 | |||
Physical activity one year before recruitment, categorical | 2,794/2,936 | 0.0055 | 2,625/5,350 | 0.0031 | ||||
- none | 17.8 | 15.8 | 37.3 | 33.5 | ||||
- < 1 h per week | 15.8 | 14.9 | 23.9 | 23.9 | ||||
- 1 to 2 h per week | 33.6 | 28.1 | 17.1 | 18.2 | ||||
- > 2 h per week | 32.0 | 35.6 | 21.7 | 24.4 |
Breast cancer risk factors | Daily coffee consumption | ||||
---|---|---|---|---|---|
≤ 1 cup | 2 to 3 cups | 4 to 5 cups | > 5 cups | Ptrenda | |
Age at menarche, continuous (y) | |||||
Mean (SD) | 13.5 (1.5) | 13.6 (1.4) | 13.6 (1.4) | 13.6 (1.5) | 0.506 |
Controls (n) in each coffee consumption category | 246 | 1,054 | 776 | 326 | |
Age at menopause, continuous (y) | |||||
Mean (SD) | 49.9 (4.1) | 50 (4.1) | 50 (3.8) | 50.2 (3.6) | 0.331 |
Controls (n) in each coffee consumption category | 268 | 1,164 | 840 | 360 | |
Body mass index, continuous (kg/m2) | |||||
Mean (SD) | 25.4 (5.1) | 25.4 (4) | 25.4 (4) | 25.4 (4.7) | 0.979 |
Controls (n) in each coffee consumption category | 264 | 1,158 | 840 | 362 | |
Alcohol consumption (g/day) | |||||
Mean (SD) | 2.1 (4.2) | 2.2 (4.0) | 2 (3.7) | 2 (4.3) | 0.411 |
Controls (n) in each coffee consumption category | 252 | 1,056 | 761 | 327 | |
Hormone replacement therapy | |||||
Proportion of ever users | 0.46 | 0.44 | 0.42 | 0.37 | 0.008
|
269 | 1,160 | 843 | 361 | ||
Family history of breast cancer | |||||
Proportion with family history of breast cancer | 0.11 | 0.10 | 0.09 | 0.08 | 0.281 |
Controls (n) in each coffee consumption category | 266 | 1,154 | 830 | 353 | |
Smoked > 1 year or > 100 cigarettes (No/Yes) | |||||
Proportion of Yes | 0.37 | 0.37 | 0.47 | 0.57 | < 0.0001
|
Controls (n) in each coffee consumption category | 270 | 1,170 | 846 | 363 | |
Parity/Age at first birth, categorical | |||||
Proportion of nulliparous | 0.14 | 0.12 | 0.09 | 0.10 | 0.876 |
Proportion of parous with age of first birth < 25 y | 0.42 | 0.47 | 0.49 | 0.50 | |
Proportion of parous with age of first birth ≥ 25 y and < 30 y | 0.30 | 0.30 | 0.26 | 0.29 | |
Proportion of parous with age of first birth ≥ 30 y | 0.14 | 0.11 | 0.15 | 0.10 | |
Controls (n) in each coffee consumption category | 270 | 1,171 | 846 | 363 | |
Education, categorical | |||||
Proportion of highest education level | |||||
to elementary school | 0.39 | 0.52 | 0.50 | 0.50 | 0.041
|
- junior secondary school | 0.25 | 0.22 | 0.23 | 0.24 | |
- high school | 0.19 | 0.14 | 0.14 | 0.15 | |
- university | 0.18 | 0.12 | 0.12 | 0.11 | |
Controls (n) in each coffee consumption category | 269 | 1,168 | 843 | 362 | |
Physical activity one year before recruitment, categorical | |||||
- none | 0.17 | 0.19 | 0.16 | 0.22 | 0.624 |
- < 1 h per week | 0.18 | 0.17 | 0.15 | 0.16 | |
- 1 to 2 h per week | 0.31 | 0.31 | 0.34 | 0.26 | |
- > 2 h per week | 0.35 | 0.33 | 0.36 | 0.36 | |
Controls (n) in each coffee consumption category | 267 | 1,165 | 842 | 362 |
Type of breast cancer | Daily coffee consumption | Controls/Cases | ORa | 95% CI | ORbc | 95% CI | ||
---|---|---|---|---|---|---|---|---|
All | ≤ 1 cup | 270/298 | 1.00 | reference | 1.00 | reference | ||
> 1 to 3 cups | 1,171/,277 | 1.00 | 0.83 | 1.20 | 1.01 | 0.84 | 1.23 | |
> 3 to 5 cups | 846/904 | 0.96 | 0.79 | 1.16 | 1.00 | 0.82 | 1.22 | |
> 5 cups | 363/328 | 0.80 | 0.64 | 0.99 | 0.84 | 0.66 | 1.06 | |
P trend | 0.028
| 0.127 | ||||||
ER-positive | ≤ 1 cup | 270/161 | 1.00 | reference | 1.00 | reference | ||
> 1 to 3 cups | 1,171/685 | 0.99 | 0.80 | 1.23 | 1.03 | 0.82 | 1.30 | |
> 3 to 5 cups | 846/501 | 0.99 | 0.79 | 1.23 | 1.07 | 0.84 | 1.36 | |
> 5 cups | 363/169 | 0.77 | 0.59 | 1.00 | 0.87 | 0.65 | 1.15 | |
P trend | 0.065 | 0.471 | ||||||
ER-negative | ≤ 1 cup | 270/48 | 1.00 | reference | 1.00 | reference | ||
> 1 to 3 cups | 1,171/148 | 0.74 | 0.52 | 1.05 | 0.77 | 0.53 | 1.11 | |
> 3 to 5 cups | 846/92 | 0.58 | 0.40 | 0.85 | 0.60 | 0.40 | 0.89 | |
> 5 cups | 363/31 | 0.44 | 0.27 | 0.71 | 0.43 | 0.25 | 0.72 | |
P trend | 0.0002
| 0.0003
| ||||||
PR-positive | ≤ 1 cup | 270/135 | 1.00 | reference | 1.00 | reference | ||
> 1 to 3 cups | 1,171/603 | 1.04 | 0.83 | 1.31 | 1.05 | 0.83 | 1.34 | |
> 3 to 5 cups | 846/434 | 1.01 | 0.80 | 1.29 | 1.09 | 0.85 | 1.40 | |
> 5 cups | 363/144 | 0.77 | 0.58 | 1.02 | 0.84 | 0.62 | 1.13 | |
P trend | 0.055 | 0.360 | ||||||
PR-negative | ≤ 1 cup | 270/66 | 1.00 | reference | 1.00 | reference | ||
> 1 to 3 cups | 1,171/212 | 0.75 | 0.55 | 1.02 | 0.85 | 0.61 | 1.17 | |
> 3 to 5 cups | 846/150 | 0.71 | 0.52 | 0.98 | 0.75 | 0.53 | 1.05 | |
> 5 cups | 363/55 | 0.59 | 0.40 | 0.88 | 0.67 | 0.44 | 1.01 | |
P trend | 0.014
| 0.034
|
Type of breast cancer | Daily coffee consumption | Controls/cases | ORa(95% CI) | ORb(95% CI) |
---|---|---|---|---|
All | ≤ 1 cup | 2,148/1,086 | 1.00 reference | 1.00 reference |
> 1 to 3 cups | 2,136/1,050 | 0.97 (0.88 to 1.08) | 0.97 (0.87 to 1.07) | |
> 3 to 5 cups | 748/358 | 0.94 (0.82 to 1.09) | 0.95 (0.82 to 1.10) | |
> 5 cups | 363/157 | 0.85 (0.70 to 1.04) | 0.87 (0.71 to 1.07) | |
P trend | 0.128 | 0.173 | ||
ER-positive | ≤ 1 cup | 2,148/854 | 1.00 reference | 1.00 reference |
> 1 to 3 cups | 2,136/822 | 0.96 (0.86 to 1.08) | 0.95 (0.85 to 1.07) | |
> 3 to 5 cups | 748/279 | 0.93 (0.79 to 1.09) | 0.94 (0.80 to 1.10) | |
> 5 cups | 363/129 | 0.90 (0.72 to 1.12) | 0.92 (0.74 to 1.15) | |
P trend | 0.221 | 0.302 | ||
ER-negative | ≤ 1 cup | 2,148/214 | 1.00 reference | 1.00 reference |
> 1 to 3 cups | 2,136/212 | 1.00 (0.82 to 1.22) | 1.02 (0.83 to 1.24) | |
> 3 to 5 cups | 748/76 | 1.04 (0.79 to 1.36) | 1.04 (0.78 to 1.37) | |
> 5 cups | 363/25 | 0.67 (0.44 to 1.03) | 0.67 (0.43 to 1.05) | |
P trend | 0.288 | 0.326 | ||
PR-positive | ≤ 1 cup | 2,148/737 | 1.00 reference | 1.00 reference |
> 1 to 3 cups | 2,136/686 | 0.93 (0.83 to 1.05) | 0.92 (0.82 to 1.04) | |
> 3 to 5 cups | 748/239 | 0.93 (0.78 to 1.10) | 0.93 (0.78 to 1.10) | |
> 5 cups | 363/115 | 0.93 (0.74 to 1.17) | 0.96 (0.76 to 1.20) | |
P trend | 0.299 | 0.363 | ||
PR-negative | ≤ 1 cup | 2,148/332 | 1.00 reference | 1.00 reference |
> 1 to 3 cups | 2,136/348 | 1.06 (0.90 to 1.24) | 1.06 (0.90 to 1.25) | |
> 3 to 5 cups | 748/116 | 1.01 (0.80 to 1.26) | 1.02 (0.81 to 1.28) | |
> 5 cups | 363/39 | 0.68 (0.48 to 0.97) | 0.70 (0.49 to 1.00) | |
P trend | 0.194 | 0.280 |