Table 2.
Distribution of reproductive factors, health status and family history of breast cancer, and corresponding odds ratios (ORs) and 95% confidence intervals (CIs) among the participants in the FRiCaM study
| Cases N (%) | Controls N (%) | OR (95% CI)a | |
|---|---|---|---|
| Age at menarche (years)b | |||
| ≤11 | 827 (25.66) | 2355 (24.39) | 1.00c |
| 12–13 | 1641 (50.92) | 4750 (49.19) | 1.00 (0.90–1.10) |
| ≥14 | 755 (23.43) | 2552 (26.43) | 0.88 (0.78–0.98) |
| P for trend | 0.0265 | ||
| Age at first live birth (years)b | |||
| <20 | 83 (3.23) | 337 (4.14) | 1.00c |
| 20–24 | 751 (29.23) | 2635 (32.36) | 1.14 (0.88–1.47) |
| 25–29 | 1077 (41.92) | 3375 (41.44) | 1.23 (0.95–1.60) |
| ≥30 | 658 (25.61) | 1797 (22.07) | 1.39 (1.07–1.81) |
| P for trend | 0.0006 | ||
| Menopausal status | |||
| Premenopause | 736 (22.28) | 2191 (22.11) | 1.00c |
| Postmenopause | 2567 (77.72) | 7718 (77.89) | 0.97 (0.86–1.10) |
| Oral contraceptives useb | |||
| Never | 2003 (65.18) | 6059 (65.74) | 1.00c |
| Ever | 1070 (34.82) | 3158 (34.26) | 1.00 (0.91–1.10) |
| Hormone replacement therapyb | |||
| Never | 2286 (73.72) | 6717 (72.84) | 1.00c |
| Ever | 815 (26.28) | 2504 (27.16) | 1.06 (0.96–1.17) |
| Previous breast biopsiesb | |||
| No | 2758 (87.28) | 8817 (92.91) | 1.00c |
| Yes | 402 (12.72) | 673 (7.09) | 1.86 (1.63–2.12) |
| Mammographic densityb | |||
| Adipose | 153 (5.15) | 817 (9.00) | 1.00c |
| <25% | 786 (26.45) | 2780 (30.61) | 1.59 (1.31–1.93) |
| 25–75% | 1160 (39.03) | 3058 (33.67) | 2.25 (1.86–2.73) |
| >75% | 186 (6.26) | 446 (4.91) | 2.61 (2.02–3.38) |
| P for trend | <0.0001 | ||
| BMI in women ≤50 years (kg/m2)b | |||
| <20 | 39 (15.54) | 107 (13.99) | 1.00a |
| 20–24.9 | 138 (54.98) | 400 (52.29) | 0.90 (0.59–1.38) |
| 25–29.9 | 56 (22.31) | 187 (24.44) | 0.75 (0.46–1.24) |
| ≥30 | 18 (7.17) | 71 (9.28) | 0.70 (0.36–1.38) |
| P for trend | 0.1803 | ||
| BMI in women >50 years (kg/m2)b | |||
| <20 | 182 (6.12) | 797 (8.94) | 1.00a |
| 20–24.9 | 1414 (47.51) | 4257 (47.76) | 1.51 (1.27–1.80) |
| 25–29.9 | 972 (32.66) | 2771 (31.09) | 1.68 (1.40–2.01) |
| ≥30 | 408 (13.71) | 1088 (12.21) | 1.89 (1.54–2.31) |
| P for trend | <0.0001 | ||
| Previous diagnosis of other cancersb | |||
| No | 2807 (94.70) | 8397 (95.59) | 1.00c |
| Yes | 157 (5.30) | 387 (4.41) | 1.19 (0.98–1.44) |
| Previous breast surgeryb | |||
| No | 2744 (87.17) | 8823 (93.29) | 1.00c |
| Yes | 404 (12.83) | 635 (6.71) | 2.01 (1.75–2.29) |
| Previous ovarian surgeryb | |||
| No | 2530 (85.16) | 7543 (84.82) | 1.00c |
| Yes | 441 (14.84) | 1350 (15.18) | 0.98 (0.87–1.10) |
| Previous Smear testb | |||
| No | 2963 (93.06) | 623 (6.55) | 1.00c |
| Yes | 221 (6.94) | 8884 (93.45) | 0.94 (0.80–1.11) |
| Previous mammographyb | |||
| No | 135 (4.19) | 432 (4.47) | 1.00c |
| Yes | 3088 (95.81) | 9241 (95.53) | 1.04 (0.85–1.27) |
| Number of first‐degree relatives affected by breast cancer | |||
| 0 | 2817 (85.29) | 9003 (90.86) | 1.00c |
| 1 | 443 (13.41) | 838 (8.46) | 1.67 (1.47–1.89) |
| ≥2 | 43 (1.30) | 68 (0.69) | 2.04 (1.38–3.00) |
| P for trend | <0.0001 | ||
a
Estimated through logistic regression models conditioned on age and year of enrollment, and adjusted for education, marital status, body mass index, alcohol drinking, age at menarche, age at first birth, menopausal status, family history of breast cancer, when appropriate. Statistically significant estimates are shown in bold.
b
The sum does not add up to the total because of missing values.
c
Reference category.