Table 1. Characteristics of index cases.
| San Francisco | Ontario | Melbourne and Sydney | Total | |
|---|---|---|---|---|
| N (%) | N (%) | N (%) | N (%) | |
| Age at diagnosis | ||||
| 20–24 years | 5 (5%) | 1 (1%) | 10 (4%) | 16 (3%) |
| 25–29 years | 13 (13%) | 23 (19%) | 57 (21%) | 93 (18%) |
| 30–34 years | 85 (83%) | 100 (81%) | 210 (76%) | 395 (78%) |
| Breast cancer family history a | ||||
| None | 88 (85%) | 107 (86%) | 252 (91%) | 447 (89%) |
| One | 15 (15%) | 15 (12%) | 21 (8%) | 51 (10%) |
| Two or more | 0 (0%) | 2 (2%) | 4 (1%) | 6 (1%) |
| BRCA1 mutation testing | ||||
| Not tested | 21 (20%) | 37 (30%) | 27 (11%) | 85 (17%) |
| Negative | 74 (72%) | 81 (65%) | 239 (85%) | 394 (78%) |
| Positive | 8 (8%) | 6 (5%) | 11 (4%)b | 25 (5%)b |
| BRCA2 mutation testing | ||||
| Not tested | 24 (23%) | 37 (30%) | 29 (10%) | 90 (18%) |
| Negative | 77 (75%) | 80 (65%) | 240 (87%) | 397 (79%) |
| Positive | 2 (2%) | 7 (6%) | 8 (3%)b | 17 (3%)b |
a
In mothers or sisters of the index case.
b
One index case had mutations in both BRCA1 and BRCA2.