Table 3.
Hazard ratios (HR) and 95% confidence intervals (CI) for the association of DXA-derived body fat measured at baseline with risk of incident, invasive breast cancer in postmenopausal women.
| Quintiles | P for trend | |||||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | ||
| Whole body fat mass | ||||||
| Cases | 77 | 87 | 112 | 106 | 121 | |
| Person-years | 25,490 | 25,188 | 25,404 | 24,935 | 24,511 | |
| Age- and energy-adjusted HR (95% CI) | 1.00 Ref. |
1.14 (0.84–1.56) |
1.47 (1.10–1.96) |
1.42 (1.06–1.91) |
1.69 (1.27–2.25) |
0.0001 |
| Multivariable-adjusted HR (95% CI)a | 1.00 Ref. |
1.18 (0.86–1.62) |
1.57 (1.16–2.13) |
1.47 (1.08–2.02) |
1.88 (1.38–2.57) |
<0.0001 |
|
| ||||||
| Whole body percent fat | ||||||
| Cases | 81 | 96 | 112 | 100 | 114 | |
| Person-years | 25,730 | 25,157 | 25,137 | 25,141 | 24,364 | |
| Age- and energy-adjusted HR (95% CI) | 1.00 Ref. |
1.21 (0.90–1.62) |
1.41 (1.06–1.88) |
1.26 (0.94–1.69) |
1.50 (1.13–1.99) |
0.007 |
| Multivariable-adjusted HR (95% CI)a | 1.00 Ref. |
1.21 (0.89–1.64) |
1.48 (1.10–1.99) |
1.28 (0.94–1.75) |
1.60 (1.18–2.18) |
0.004 |
|
| ||||||
| Fat mass of trunk | ||||||
| Cases/person-years | 79 | 94 | 97 | 106 | 127 | |
| Person-years | 25,770 | 25,353 | 25,252 | 24,689 | 24,466 | |
| Age- and energy-adjusted HR (95% CI) | 1.00 Ref. |
1.21 (0.89–1.63) |
1.24 (0.92–1.67) |
1.41 (1.05–1.88) |
1.74 (1.31–2.31) |
<0.0001 |
| Multivariable-adjusted HR (95% CI)a | 1.00 Ref. |
1.31 (0.96–1.78) |
1.34 (0.98–1.83) |
1.56 (1.15–2.14) |
2.05 (1.50–2.79) |
<0.0001 |
|
| ||||||
| Fat mass of right leg | ||||||
| Cases | 81 | 86 | 107 | 109 | 120 | |
| Person-years | 24,666 | 25,231 | 25,522 | 25,276 | 24,835 | |
| Age- and energy-adjusted HR (95% CI) | 1.00 Ref. |
1.05 (0.78–1.43) |
1.30 (0.98–1.74) |
1.34 (1.01–1.79) |
1.53 (1.15–2.04) |
0.0008 |
| Multivariable-adjusted HR (95% CI)a | 1.00 Ref. |
1.00 (0.73–1.36) |
1.26 (0.93–1.69) |
1.29 (0.95–1.74) |
1.53 (1.14–2.07) |
0.001 |
|
| ||||||
| Fat mass of left leg | ||||||
| Cases | 78 | 91 | 109 | 101 | 124 | |
| Person-years | 24,586 | 25,501 | 25,321 | 25,386 | 24,736 | |
| Age- and energy-adjusted HR (95% CI) | 1.00 Ref. |
1.14 (0.84–1.54) |
1.38 (1.03–1.85) |
1.28 (0.95–1.72) |
1.64 (1.24–2.19) |
0.0004 |
| Multivariable-adjusted HR (95% CI)a | 1.00 Ref. |
1.05 (0.77–1.43) |
1.33 (0.99–1.79) |
1.19 (0.87–1.62) |
1.63 (1.21–2.20) |
0.0007 |
|
| ||||||
| Ratio of trunk fat mass to average of R and L leg fat mass | ||||||
| Cases | 74 | 117 | 104 | 104 | 104 | |
| Person-years | 25,932 | 25,391 | 25,388 | 24,864 | 23,955 | |
| Age- and energy-adjusted HR (95% CI) | 1.00 Ref. |
1.61 (1.20–2.15) |
1.43 (1.06–1.93) |
1.45 (1.08–1.96) |
1.51 (1.12–2.04) |
0.04 |
| Multivariable-adjusted HR (95% CI)a | 1.00 Ref. |
1.68 (1.25–2.28) |
1.51 (1.10–2.06) |
1.60 (1.17–2.18) |
1.77 (1.29–2.42) |
0.004 |
aAdjusted for age at enrollment, education, ethnicity, family history of breast cancer, age at menarche, age at first full-term birth, parity, age at menopause, oral contraceptive use, duration of hormone therapy, previous breast biopsy, physical activity, alcohol intake, pack-years of smoking, intake of energy, and randomization status.