Table 2.
The association between body mass index and breast cancer risk in Asian women by menopausal status at baseline
| Body mass index at baseline (kg/m2) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| < 18.5 | 18.5– < 21 | 21– < 23 | 23– < 25 | 25– < 27.5 | 27.5– < 30 | 30- | Trend (per 5 kg/m2) | ||
| HR (95% CI) | HR (95% CI) | HR | HR (95% CI) | HR (95% CI) | HR (95% CI) | HR (95% CI) | HR (95% CI) | p | |
| Premenopausal women | |||||||||
| Number of participants | 5,862 | 27,243 | 32,295 | 26,556 | 17,294 | 6,566 | 2,970 | ||
| Person-years | 115,078 | 509,956 | 589,871 | 483,623 | 315,679 | 119,619 | 53,686 | ||
| Number of cases | 92 | 470 | 578 | 496 | 370 | 135 | 61 | ||
| Crude rate (per 100,000) | 79.95 | 92.16 | 97.99 | 102.56 | 117.21 | 112.86 | 113.62 | ||
| Age- and study-adjusted (HR1) | 0.86 (0.69–1.07) | 0.97 (0.86–1.10) | 1 (ref.) | 1.01 (0.89–1.14) | 1.12 (0.99–1.28) | 1.07 (0.89–1.29) | 1.11 (0.85–1.44) | 1.08 (1.01–1.16) | 0.02 |
| Multivariate-adjusted (HR2)a | 0.86 (0.69–1.07) | 0.97 (0.86–1.10) | 1 (ref.) | 1.01 (0.90–1.14) | 1.13 (0.99–1.28) | 1.07 (0.89–1.29) | 1.11 (0.85–1.44) | 1.08 (1.01–1.16) | 0.02 |
| Multivariate-adjusted (HR3)b | 0.83 (0.67–1.04) | 0.96 (0.85–1.08) | 1 (ref.) | 1.01 (0.90–1.14) | 1.13 (0.99–1.29) | 1.08 (0.89–1.30) | 1.11 (0.85–1.44) | 1.09 (1.02–1.17) | 0.01 |
| (Excluding cases within 3 years) | |||||||||
| Multivariate-adjusted (HR2)a | 0.85 (0.66–1.08) | 0.93 (0.81–1.07) | 1 (ref.) | 1.01 (0.89–1.16) | 1.13 (0.98–1.30) | 1.13 (0.93–1.38) | 1.03 (0.77–1.39) | 1.10 (1.02–1.18) | 0.01 |
| Multivariate-adjusted (HR3)b | 0.82 (0.64–1.05) | 0.92 (0.80–1.05) | 1 (ref.) | 1.01 (0.89–1.16) | 1.14 (0.99–1.31) | 1.15 (0.94–1.40) | 1.03 (0.77–1.39) | 1.11 (1.03–1.20) | 0.005 |
| Postmenopausal women | |||||||||
| Number of participants | 11,885 | 34,326 | 46,852 | 45,963 | 37,651 | 16,091 | 7,635 | ||
| Person-years | 167,878 | 526,765 | 734,224 | 727,835 | 595,491 | 254,248 | 117,526 | ||
| Number of cases | 98 | 331 | 526 | 669 | 564 | 276 | 153 | ||
| Crude rate (per 100,000) | 58.38 | 62.84 | 71.64 | 91.92 | 94.71 | 108.56 | 130.18 | ||
| Age- and study-adjusted (HR1) | 0.83 (0.67–1.03) | 0.89 (0.77–1.02) | 1 (ref.) | 1.26 (1.12–1.41) | 1.27 (1.13–1.43) | 1.40 (1.21–1.62) | 1.64 (1.37–1.96) | 1.28 (1.21–1.35) | < 0.001 |
| Multivariate-adjusted (HR2)a | 0.83 (0.67–1.03) | 0.89 (0.77–1.02) | 1 (ref.) | 1.26 (1.12–1.41) | 1.27 (1.13–1.44) | 1.40 (1.21–1.62) | 1.64 (1.37–1.97) | 1.28 (1.22–1.35) | < 0.001 |
| Multivariate-adjusted (HR4)c | 0.80 (0.64–1.00) | 0.87 (0.76–1.00) | 1 (ref.) | 1.27 (1.13–1.42) | 1.30 (1.15–1.46) | 1.43 (1.24–1.66) | 1.72 (1.43–2.06) | 1.32 (1.25–1.39) | < 0.001 |
| (Excluding cases within 3 years) | |||||||||
| Multivariate-adjusted (HR2)a | 0.80 (0.63–1.02) | 0.87 (0.75–1.02) | 1 (ref.) | 1.22 (1.08–1.39) | 1.28 (1.12–1.46) | 1.46 (1.24–1.71) | 1.72 (1.42–2.10) | 1.31 (1.24–1.39) | < 0.001 |
| Multivariate-adjusted (HR4)c | 0.77 (0.60–0.99) | 0.85 (0.73–1.00) | 1 (ref.) | 1.23 (1.08–1.40) | 1.31 (1.14–1.49) | 1.50 (1.28–1.75) | 1.80 (1.48–2.19) | 1.35 (1.27–1.43) | < 0.001 |
HR hazard ratio, CI confident interval, ref reference
aEstimated hazard ratio after adjustments for age at enrollment (continuous), study (13 cohorts), smoking status (never, former, current smokers), and alcohol consumption (non-drinkers or current drinkers)
bEstimated hazard ratio after adjustments for age at enrollment (continuous), study (13 cohorts), smoking status (never, former, current smokers), alcohol consumption (non-drinkers or current drinkers), age at menarche (≤ 10 y, 11–12 y, 13–14 y, 15–16 y, ≥ 17 y), nulliparity (yes, no), and age at first delivery (≤ 20 y, 21–25 y, 26–30 y, ≥ 31 y)
cEstimated hazard ratio after adjustments for age at enrollment (continuous), study (13 cohorts), smoking status (never, former, current smokers), alcohol consumption (non-drinkers or current drinkers), age at menarche (≤ 10 y, 11–12 y, 13–14 y, 15–16 y, ≥ 17 y), nulliparity (yes, no), age at first delivery (≤ 20 y, 21–25 y, 26–30 y, ≥ 31 y), and age at menopause (≤ 44 y, 45–49 y, 50–54 y, ≥ 55 y)