Table 1.
Associations between reproductive and other risk factors and breast cancer characterized by ESR1 A908G mutation status
| Risk factor | Controls (n = 790) | Mutation-positive cases (n = 37) | Mutation-negative cases (n = 616) | |||||||||||
| n | (%) | n | (%) | OR1a | 95% CI | OR2b | 95% CI | n | (%) | OR1a | 95% CI | OR2b | 95% CI | |
| Age (years) | ||||||||||||||
| 50+ | 383 | (48.5) | 19 | (51.4) | c | c | 246 | (39.9) | c | c | ||||
| <50 | 407 | (51.5) | 18 | (48.6) | 370 | (60.1) | ||||||||
| Race | ||||||||||||||
| White | 458 | (58.0) | 25 | (67.6) | c | c | 371 | (60.2) | c | c | ||||
| African-American | 332 | (42.0) | 12 | (32.4) | 245 | (39.8) | ||||||||
| Menopausal status | ||||||||||||||
| Postmenopausal | 435 | (55.1) | 22 | (59.5) | 1.00 | --- | 1.00d | --- | 295 | (47.9) | 1.00 | --- | 1.00d | --- |
| Premenopausal | 355 | (44.9) | 15 | (40.5) | 1.27 | 0.40–4.05 | 1.63 | 0.47–5.64 | 321 | (52.1) | 1.08 | 0.78–1.50 | 1.12 | 0.80–1.58 |
| First-degree family history of BC | ||||||||||||||
| No | 671 | (88.3) | 26 | (72.2) | 1.00 | --- | 1.00e | --- | 523 | (87.0) | 1.00 | --- | 1.00e | --- |
| Yes | 89 | (11.7) | 10 | (27.8) | 2.54 | 1.16–5.55 | 2.69 | 1.15–6.28 | 78 | (13.0) | 1.17 | 0.84–1.62 | 1.22 | 0.87–1.71 |
| First-degree family history of BC and/or ovarian cancer | ||||||||||||||
| No | 664 | (87.4) | 24 | (66.7) | 1.00 | --- | 1.00e | --- | 514 | (85.5) | 1.00 | --- | 1.00e | --- |
| Yes | 96 | (12.6) | 12 | (33.3) | 3.13 | 1.49–6.58 | 3.48 | 1.56–7.76 | 87 | (14.5) | 1.21 | 0.88–1.66 | 1.27 | 0.92–1.76 |
| Prior benign breast biopsy | ||||||||||||||
| No | 649 | (82.4) | 28 | (80.0) | 1.00 | --- | 1.00 | --- | 518 | (84.2) | 1.00 | --- | 1.00 | --- |
| Yes | 139 | (17.6) | 7 | (20.0) | 1.21 | 0.51–2.87 | 1.17 | 0.47–2.91 | 97 | (15.8) | 1.00 | 0.75–1.33 | 0.94 | 0.70–1.28 |
| BMI | ||||||||||||||
| <25 | 250 | (32.2) | 15 | (41.7) | 1.00 | --- | 1.00f | --- | 224 | (37.1) | 1.00 | --- | 1.00f | --- |
| 25 to <30 | 250 | (32.2) | 10 | (27.8) | 0.73 | 0.32–1.69 | 0.78 | 0.32–1.90 | 180 | (29.8) | 0.87 | 0.66–1.14 | 0.83 | 0.63–1.10 |
| 30+ | 277 | (35.6) | 11 | (30.5) | 0.80 | 0.34–1.89 | 0.76 | 0.29–1.98 | 200 | (33.1) | 0.85 | 0.64–1.12 | 0.80 | 0.60–1.08 |
| Smoking | ||||||||||||||
| Never | 423 | (53.5) | 18 | (48.7) | 1.00 | --- | 1.00g | --- | 322 | (52.3) | 1.00 | --- | 1.00g | --- |
| Ever | 367 | (46.5) | 19 | (51.3) | 1.16 | 0.59–2.27 | 1.04 | 0.49–2.19 | 294 | (47.7) | 1.08 | 0.87–1.34 | 1.11 | 0.88–1.41 |
| Alcohol consumption | ||||||||||||||
| Never | 231 | (29.3) | 14 | (37.8) | 1.00 | --- | 1.00h | --- | 178 | (28.9) | 1.00 | --- | 1.00h | --- |
| Ever | 558 | (70.7) | 23 | (62.2) | 0.79 | 0.39–1.63 | 0.74 | 0.32–1.71 | 438 | (71.1) | 0.95 | 0.75–1.22 | 0.88 | 0.67–1.16 |
| Age at menarche (years) | ||||||||||||||
| 14+ | 203 | (25.8) | 10 | (27.0) | 1.00 | --- | 1.00i | --- | 130 | (21.1) | 1.00 | --- | 1.00i | --- |
| 13 | 206 | (26.2) | 9 | (24.3) | 0.96 | 0.38–2.44 | 1.22 | 0.43–3.41 | 165 | (26.8) | 1.28 | 0.95–1.75 | 1.38 | 1.01–1.91 |
| ≤12 | 378 | (48.0) | 18 | (48.6) | 1.12 | 0.50–2.50 | 1.42 | 0.57–3.53 | 321 | (52.1) | 1.36 | 1.04–1.79 | 1.46 | 1.09–1.94 |
| Parity | ||||||||||||||
| Nulliparous | 89 | (11.3) | 5 | (13.5) | 1.00 | --- | 1.00j | --- | 100 | (16.2) | 1.00 | --- | 1.00j | --- |
| Parous | 701 | (88.7) | 32 | (86.5) | 0.93 | 0.34–2.54 | 1.30 | 0.44–3.85 | 516 | (83.8) | 0.76 | 0.55–1.04 | 0.92 | 0.65–1.29 |
| Age at first full-term pregnancy (years) | ||||||||||||||
| Nulliparous | 89 | (11.3) | 5 | (13.9) | 1.00 | --- | 1.00j | --- | 100 | (16.3) | 1.00 | --- | 1.00j | --- |
| 10–19 | 236 | (29.9) | 8 | (22.2) | 0.74 | 0.23–2.39 | 1.03 | 0.28–3.79 | 181 | (29.5) | 0.82 | 0.57–1.16 | 0.99 | 0.67–1.46 |
| 20–24 | 265 | (33.6) | 11 | (30.5) | 0.82 | 0.27–2.52 | 1.14 | 0.35–3.74 | 181 | (29.5) | 0.73 | 0.51–1.03 | 0.88 | 0.60–1.27 |
| 25+ | 198 | (25.2) | 12 | (33.3) | 1.20 | 0.40–3.63 | 1.71 | 0.51–5.78 | 152 | (24.8) | 0.73 | 0.51–1.05 | 0.90 | 0.60–1.34 |
| Number full-term births | ||||||||||||||
| Nulliparous | 89 | (11.3) | 5 | (13.5) | 1.00 | --- | 1.00j | --- | 100 | (16.2) | 1.00 | --- | 1.00j | --- |
| 1 | 141 | (17.8) | 5 | (13.5) | 0.74 | 0.20–2.69 | 0.99 | 0.26–3.78 | 117 | (19.0) | 0.79 | 0.54–1.17 | 0.89 | 0.59–1.34 |
| 2 or more | 560 | (70.9) | 27 | (73.0) | 0.98 | 0.36–2.72 | 1.43 | 0.47–4.35 | 399 | (64.8) | 0.75 | 0.54–1.03 | 0.92 | 0.65–1.31 |
| Breastfeeding | ||||||||||||||
| Never | 476 | (60.3) | 26 | (70.3) | 1.00 | --- | 1.00k | --- | 413 | (67.0) | 1.00 | --- | 1.00k | --- |
| Ever | 314 | (39.7) | 11 | (29.7) | 0.52 | 0.25–1.09 | 0.29 | 0.12–0.71 | 203 | (33.0) | 0.70 | 0.56–0.87 | 0.69 | 0.53–0.89 |
| Age at menopause (years) (postmenopausal) | ||||||||||||||
| <45 | 192 | (45.6) | 10 | (45.5) | 1.00 | - | 1.00d | --- | 117 | (39.9) | 1.00 | --- | 1.00d | --- |
| 45–49 | 119 | (28.3) | 7 | (31.8) | 1.13 | 0.42–3.08 | 1.47 | 0.45–4.79 | 93 | (31.7) | 1.38 | 0.96–1.97 | 1.39 | 0.95–2.03 |
| 50+ | 110 | (26.1) | 5 | (22.7) | 0.82 | 0.27–2.53 | 1.32 | 0.36–4.77 | 83 | (28.3) | 1.39 | 0.95–2.03 | 1.50 | 1.00–2.24 |
| Duration of ovarian function (years) (postmenopausal) | ||||||||||||||
| ≤29 | 139 | (33.2) | 6 | (27.2) | 1.00 | --- | 1.00d | --- | 79 | (27.0) | 1.00 | --- | 1.00d | --- |
| 30–35 | 141 | (33.6) | 10 | (45.4) | 1.66 | 0.58–4.74 | 1.78 | 0.49–6.46 | 98 | (33.4) | 1.33 | 0.90–1.95 | 1.32 | 0.88–1.99 |
| 36+ | 139 | (33.2) | 6 | (27.2) | 0.98 | 0.30–3.18 | 1.38 | 0.35–5.45 | 116 | (39.6) | 1.69 | 1.15–2.48 | 1.82 | 1.21–2.74 |
| Ptrend | 0.97 | 0.70 | 0.007 | 0.004 | ||||||||||
aOR1 minimally adjusted for age, race, and offsets.
bOR2 adjusted for age, race, offsets, menopausal status (except d), family history of breast cancer (except e), BMI (<25, 25 to <30, 30+) (except f), smoking status (never, former, current) (except g), alcohol intake (ever, never) (except h), age at menarche (<11, 11–12, 13, 14+) (except i), parity/age first full-term pregnancy (except j), and breast feeding (never, ever) (except k).
cORs were not calculated for age or race as these factors were part of the sampling scheme. BC, breast cancer; BMI, body mass index; CI, confidence interval; ESR1, estrogen receptor alpha; OR, odds ratio.