From: Breastfeeding and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers
Characteristic | BRCA1 | BRCA2 | ||||
---|---|---|---|---|---|---|
 | Controls (n = 1,243) | Cases (n = 1,243) | P | Controls (n = 422) | Cases (n = 422) | P |
Year of birth, mean (range) | 1957.5 (1920-1980) | 1957.3 (1920-1980) | 0.71 | 1954.4 (1924-1978) | 1955.3 (1924-1978) | 0.82 |
Age at diagnosis, mean (range) | n/a1 | 0.71 | n/a1 | n/a1 | 42.7 (24-67) | n/a1 |
Country of residence, n (%) | Â | Â | Â | Â | Â | Â |
Poland | 601 (48%) | matched | Â | 0 (0%) | matched | Â |
USA | 323 (26%) | Â | Â | 187 (44%) | Â | Â |
Canada | 265 (21%) | Â | Â | 218 (52%) | Â | Â |
Israel | 29 (2%) | Â | Â | 13 (3%) | Â | Â |
Austria | 18 (1.5%) | Â | Â | 3 (0.7%) | Â | Â |
Italy | 5 (0.4%) | Â | Â | 0 (0%) | Â | Â |
United Kingdom | 2 (0.2%) | Â | Â | 2 (0.5%) | Â | Â |
Age at menarche, mean (range) | 13.27(8-28) | 13.09 (9-21) | 0.003 | 12.64 (8-28) | 12.15 (9-17) | 0.88 |
Age at first birth, mean (range) | 25.1 (15-44) | 24.8 (15-42) | 0.08 | 26.6 (17-44) | 26.3 (16-42) | 0.37 |
Age at last birth, mean (range) | 29.3 (16-45) | 29.0 (17-44) | 0.06 | 30.5 (20-45) | 30.2 (18-43) | 0.96 |
Parity2,4, n (%) | Â | Â | Â | Â | Â | Â |
1 | 235 (19%) | Â | Â | 65 (15%) | Â | Â |
2 | 663 (53%) | Â | Â | 233 (55%) | Â | Â |
3 | 280 (23%) | Â | Â | 100 (24%) | Â | Â |
≥ 4 | 65 (5%) |  |  | 24 (6%) |  |  |
Mean (range) | 2.16 (1-6) | matched | Â | 2.20 (1-6) | matched | Â |
Breastfeeding, mean months3,4 (range) | 10.4 (0-92) | 8.8 (0-84) | 0.0009 | 9.7 (0-94) | 10.2 (0-86) | 0.56 |
Oral contraceptive use4, ever, n (%) | 644 (52%) | 657 (53%) | 0.95 | 348 (83.5%) | 336 (80.2%) | 0.22 |
Smoking status, ever, n (%) | 549 (45%) | 574 (46%) | 0.74 | 185 (44.4%) | 170 (40.9%) | 0.31 |
Alcohol use, ever, n (%) | 832 (67%) | 760 (61%) | 0.002 | 305 (73.3%) | 284 (68.8%) | 0.13 |
HRT use4, n (%) | 148 (12%) | 67 (5%) | < 0.0001 | 69 (16.5%) | 45 (10.7%) | 0.02 |
BMI at age 30, mean (range) | 22.5 (13-47) | 22.6 (9-62) | 0.24 | 22.8 (15-54) | 23.0 (12-65) | 0.48 |