Relationship between age at menarche, breast feeding history, and risk of breast cancer subtypesa
Luminal A | Luminal B | Triple-negative | HER2-overexpressing | ||||
---|---|---|---|---|---|---|---|
n (%) | n (%) | OR (95% CI) | n (%) | OR (95% CI) | n (%) | OR (95% CI) | |
Age at menarche | |||||||
<12 | 105 (19.8) | 17 (21.5) | 1.00 (ref) | 169 (22.1) | 1.00 (ref) | 64 (21.6) | 1.00 (ref) |
12–13 | 308 (58.0) | 49 (62.0) | 0.95 (0.52–1.73) | 439 (57.4) | 0.90 (0.67–1.19) | 167 (56.4) | 0.88 (0.61–1.26) |
≥14 | 118 (22.2) | 13 (16.5) | 0.64 (0.30–1.39) | 157 (20.5) | 0.83 (0.59–1.16) | 65 (22.0) | 0.88 (0.57–1.36) |
Every 2-year | 0.89 (0.65–1.22) | 0.92 (0.79–1.06) | 0.98 (0.81–1.18) | ||||
Ptrend | 0. 474 | 0.246 | 0.828 | ||||
Ever breast fed a childb | |||||||
No | 85 (21.3) | 8 (14.0) | 1.00 (ref) | 144 (25.0) | 1.00 (ref) | 58 (23.7) | 1.00 (ref) |
Yes | 314 (78.7) | 49 (86.0) | 1.30 (0.57–2.94) | 432 (75.0) | 0.77 (0.56–1.06) | 187 (76.3) | 0.80 (0.54–1.19) |
Breast feeding duration (in months)b | |||||||
Never | 85 (21.3) | 8 (14.0) | 1.00 (ref) | 144 (25.0) | 1.00 (ref) | 58 (23.7) | 1.00 (ref) |
< 6 | 124 (31.1) | 13 (22.8) | 0.90 (0.35–2.33) | 165 (28.6) | 0.75 (0.52–1.07) | 63 (25.7) | 0.69 (0.44–1.10) |
6–11 | 71 (17.8) | 9 (15.8) | 1.08 (0.38–3.01) | 105 (18.2) | 0.83 (0.55–1.25) | 50 (20.4) | 0.95 (0.57–1.57) |
12–23 | 64 (16.0) | 11 (19.3) | 1.37 (0.50–3.72) | 94 (16.3) | 0.82 (0.53–1.26) | 34 (13.9) | 0.71 (0.41–1.22) |
24–35 | 32 (8.0) | 7 (12.3) | 1.79 (0.58–5.53) | 47 (8.2) | 0.82 (0.48–1.40) | 20 (8.2) | 0.83 (0.43–1.62) |
36+ | 23 (5.8) | 9 (15.8) | 3.47 (1.17–10.33)c | 21 (3.6) | 0.51 (0.27–0.99)c | 20 (8.2) | 1.18 (0.59–2.37) |
Every 6 months | 1.13 (1.03–1.23)c | 0.96 (0.91–1.02) | 1.01 (0.95–1.08) | ||||
Ptrend | 0.008 | 0.151 | 0.716 |