From: Risk factors for breast cancer characterized by the estrogen receptor alpha A908G (K303R) mutation
Risk factor | Controls (n= 790) | Mutation-positive cases (n= 37) | Mutation-positive cases vs. controls | Mutation-negative cases (n= 616) | Mutation-negative cases vs. controls | Mutation-positive vs. mutation-negative cases | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
 | n | (%) | n | (%) | ORa | 95% CI | n | (%) | ORa | 95% CI | ORa | 95% CI |
OC use | ||||||||||||
   Never | 319 | (40.4) | 14 | (37.8) | 1.00 | --- | 224 | (36.5) | 1.00 | --- | 1.00 | --- |
   Ever | 470 | (59.6) | 23 | (62.2) | 1.72 | 0.66–4.44 | 390 | (63.5) | 1.15 | 0.87–1.52 | 1.53 | 0.61–3.84 |
OC duration | ||||||||||||
   Never | 319 | (40.4) | 14 | (37.8) | 1.00 | --- | 224 | (36.5) | 1.00 | --- | 1.00 | --- |
   <5 years | 232 | (29.4) | 8 | (21.6) | 1.08 | 0.35–3.38 | 194 | (31.6) | 1.27 | 0.94–1.73 | 1.01 | 0.33–3.06 |
   5–10 years | 162 | (20.5) | 8 | (21.6) | 1.75 | 0.53–5.77 | 123 | (20.0) | 0.95 | 0.67–1.35 | 1.79 | 0.59–5.43 |
   >10 years | 76 | (9.6) | 7 | (8.9) | 3.73 | 1.16–12.03 | 73 | (11.9) | 1.18 | 0.77–1.81 | 2.66 | 0.81–8.67 |
   Ptrend |  |  |  |  |  | 0.02 |  |  |  | 0.84 |  | 0.07 |
Age at first use of OCs | ||||||||||||
   Never | 319 | (40.4) | 14 | (37.8) | 1.00 | --- | 224 | (36.6) | 1.00 | --- | 1.00 | --- |
   ≤20 years | 215 | (27.2) | 8 | (21.6) | 1.18 | 0.32–4.42 | 192 | (31.4) | 0.99 | 0.69–1.41 | 1.44 | 0.41–5.09 |
   >20 years | 255 | (32.3) | 15 | (40.5) | 1.81 | 0.71–4.63 | 196 | (32.0) | 1.20 | 0.89–1.60 | 1.56 | 0.61–3.96 |
Age at last use of OCs | ||||||||||||
   Never | 319 | (40.4) | 14 | (37.8) | 1.00 | --- | 224 | (36.6) | 1.00 | --- | 1.00 | --- |
   ≤30 years | 273 | (34.6) | 10 | (27.0) | 1.18 | 0.36–3.90 | 226 | (36.9) | 1.10 | 0.80–1.52 | 1.39 | 0.45–4.25 |
   >30 years | 197 | (25.0) | 13 | (35.1) | 1.97 | 0.75–5.15 | 162 | (26.5) | 1.16 | 0.85–1.58 | 1.63 | 0.62–4.29 |
Year of first OC use | ||||||||||||
   Never | 319 | (40.4) | 14 | (37.8) | 1.00 | --- | 224 | (36.6) | 1.00 | --- | 1.00 | --- |
   ≤1975 | 389 | (49.3) | 19 | (51.4) | 1.72 | 0.67–4.43 | 292 | (47.7) | 1.15 | 0.87–1.52 | 1.54 | 0.61–3.89 |
   >1975 | 81 | (10.3) | 4 | (10.8) | 1.51 | 0.28–8.12 | 96 | (15.7) | 0.98 | 0.62–1.55 | 1.58 | 0.35–7.13 |
First use before first full-term pregnancy | ||||||||||||
   No | 233 | (54.8) | 11 | (57.9) | 1.00 | --- | 169 | (51.1) | 1.00 | --- | 1.00 | --- |
   Yes | 192 | (45.2) | 8 | (42.1) | 0.66 | 0.15–2.93 | 162 | (48.9) | 1.12 | 0.76–1.66 | 0.78 | 0.18–3.31 |
Recency of OC use (years since stopping) | ||||||||||||
   Never | 319 | (42.3) | 14 | (37.8) | 1.00 | --- | 224 | (39.4) | 1.00 | --- | 1.00 | --- |
   10+ | 374 | (49.5) | 17 | (45.9) | 1.70 | 0.65–4.43 | 278 | (48.8) | 1.15 | 0.86–1.52 | 1.52 | 0.59–3.92 |
   <10 | 62 | (8.2) | 6 | (16.2) | 3.63 | 0.80–16.45 | 67 | (11.8) | 1.06 | 0.65–1.72 | 3.65 | 0.86–15.47 |
   Ptrend |  |  |  |  |  | 0.10 |  |  |  | 0.56 |  | 0.10 |
OC duration and recency of use (years since stopping) | ||||||||||||
   Never | 319 | (42.3) | 14 | (37.8) | 1.00 | --- | 224 | (39.4) | 1.00 | --- | 1.00 | --- |
   <10, <10 | 31 | (4.1) | 2 | (5.4) | 1.43 | 0.19–10.77 | 32 | (5.6) | 0.84 | 0.44–1.58 | 3.04 | 0.46–20.06 |
   <10, 10+ | 315 | (41.7) | 13 | (35.1) | 1.53 | 0.55–4.26 | 245 | (43.1) | 1.21 | 0.90–1.62 | 1.25 | 0.46–3.41 |
   10+, <10 | 31 | (4.1 | 4 | (10.8) | 6.49 | 1.32–31.89 | 35 | (6.2) | 1.32 | 0.73–2.38 | 3.53 | 0.73–17.09 |
   10+, 10+ | 59 | (7.8) | 4 | (10.8) | 1.93 | 0.52–7.11 | 33 | (5.8) | 0.81 | 0.49–1.35 | 3.01 | 0.78–11.59 |
Postmenopausal HRT use | ||||||||||||
   Never | 219 | (50.3) | 13 | (59.1) | 1.00 | --- | 180 | (61.0) | 1.00 | --- | 1.00 | --- |
   Ever | 216 | (49.7) | 9 | (40.9) | 0.83 | 0.28–2.42 | 115 | (39.0) | 0.62 | 0.44–0.87 | 1.23 | 0.42–3.61 |
Postmenopausal HRT duration | ||||||||||||
   Never | 219 | (50.3) | 13 | (59.1) | 1.00 | --- | 180 | (61.0) | 1.00 | --- | 1.00 | --- |
   <5 years | 105 | (24.1) | 3 | (13.6) | 0.60 | 0.14–2.51 | 56 | (19.0) | 0.61 | 0.40–0.92 | 1.37 | 0.30–6.24 |
   5+ years | 111 | (25.6) | 6 | (27.3) | 1.07 | 0.31–3.70 | 59 | (20.0) | 0.64 | 0.42–0.96 | 1.17 | 0.35–3.91 |