Table 4 Association between mammographic density and other selected risk factors, and risk of invasive breast cancer stratified by pathologic subtype in the NBCSP case-control study
Hormone receptor-positive and HER2-negative breast cancer | HER2-positive breast cancer | Hormone receptor-negative and HER2-negative breast cancer | |||||||
|---|---|---|---|---|---|---|---|---|---|
Baseline risk factor | No. of controls (%) | No. of cases (%) | Odds ratioa(95% CI) | No. of cases (%) | Odds ratioa(95% CI) | No. of cases (%) | Odds ratioa(95% CI) | ||
Age at first live birthb | |||||||||
5-year increase | 4,048 (86.8) | 534 (82.0) | 1.15 (1.02-1.28) | 94 (84.7) | 1.13 (0.88-1.44) | 57 (79.2) | 0.72 (0.49-1.06) | ||
Nulliparous | 618 (13.2) | 117 (18.0) | 1.31 (1.03-1.66) | 17 (15.3) | 1.04 (0.58-1.86) | 15 (20.8) | 1.23 (0.63-2.39) | ||
Age at menopausec | |||||||||
5-year increase | 3,040 (65.2) | 415 (63.8) | 1.11 (0.98-1.27) | 62 (55.9) | 1.36 (0.97-0.69) | 50 (69.4) | 1.01 (0.68-1.51) | ||
Premenopausal | 1,626 (34.8) | 236 (36.3) | 1.15 (0.87-1.51) | 49 (44.1) | 1.29 (0.69-2.43) | 22 (30.6) | 0.88 (0.40-1.92) | ||
Family history of breast cancer | |||||||||
None | 4,055 (86.9) | 538 (82.6) | 1.00 (reference) | 90 (81.1) | 1.00 (reference) | 54 (75.0) | 1.00 (reference) | ||
Second-degree relative | 325 (7.0) | 66 (10.1) | 1.46 (1.09-1.95) | 11 (9.9) | 1.51 (0.76-3.01) | 4 (5.6) | 0.67 (0.22-2.01) | ||
First-degree relative ≥ 50 years | 172 (3.7) | 29 (4.5) | 1.13 (0.74-1.73) | 4 (3.6) | 1.26 (0.43-3.68) | 8 (11.1) | 2.28 (0.94-5.48) | ||
First-degree relative < 50 years | 114 (2.4) | 18 (2.8) | 1.10 (0.65-1.87) | 6 (5.4) | 2.82 (1.10-7.20) | 6 (8.3) | 3.59 (1.25-10.33) | ||
Previous breast biopsy | |||||||||
No | 4,263 (91.4) | 547 (84.0) | 1.00 (reference) | 98 (88.3) | 1.00 (reference) | 59 (81.9) | 1.00 | ||
Yes | 403 (8.6) | 104 (16.0) | 1.80 (1.40-1.32) | 13 (11.7) | 1.39 (0.74-2.60) | 13 (18.1) | 1.84 (0.90-3.76) | ||
Mammographic density (%) | |||||||||
0-10 | 1,710 (36.6) | 154 (23.7) | 1.00 (reference) | 24 (21.6) | 1.00 (reference) | 16 (22.2) | 1.00 (reference) | ||
11-25 | 1,136 (24.3) | 143 (22.0) | 1.44 (1.12-1. 85) | 27 (24.3) | 1.58 (0.88-2.82) | 13 (18.1) | 1.27 (0.56-2.89) | ||
26-50 | 1,157 (24.8) | 202 (31.0) | 2.01 (1.57-2. 57) | 42 (37.8) | 2.61 (1.47-4.63) | 29 (40.3) | 3.18 (1.54-6.55) | ||
> 50 | 663 (14.2) | 152 (23.3) | 2.60 (1.95-3. 45) | 18 (16.2) | 1.68 (0.83-3.41) | 14 (19.4) | 3.15 (1.26-7.84) | ||
P value for trendd | <0.001 | 0.024 | 0.001 | ||||||