Table 1 Characteristics of all study participants and stratified by BRCA1 mutation status
| Characteristic |
All (n = 58) |
BRCA1
+/+
(n = 36) |
BRCA1
+/−
(n = 22) | P |
|---|---|---|---|---|
| Age (years), mean (range) | 38 (18–62) | 34.4 (18–62) | 43.6 (27–62) | 0.007 |
| Ethnicity, n (%) | ||||
| Other white | 34 (59 %) | 20 (56 %) | 14 (64 %) | 0.04 |
| Ashkenazi Jewish | 10 (17 %) | 3 (8 %) | 7 (32 %) | |
| Hispanic | 3 (5 %) | 3 (8 %) | 0 (0 %) | |
| East Asian | 7 (12 %) | 6 (17 %) | 1 (4 %) | |
| South Asian | 4 (7 %) | 4 (11 %) | 0 (0 %) | |
| Parous, ever, n (%) | 29 (50 %) | 12 (33.3 %) | 17 (77.3 %) | 0.003 |
| Breastfeeding, ever, n (%)a | 23 (79 %) | 10 (83 %) | 13 (76 %) | 1.00 |
| Age at menarche (years), mean (SD) | 12.4 (1.4) | 12.2 (1.2) | 12.7 (1.7) | 0.20 |
| Postmenopausal, n (%) | 17 (29 %) | 4 (11 %) | 13 (59 %) | <0.001 |
| Current oral contraceptive use, yes, n (%) | 6 (10 %) | 4 (11 %) | 2 (9 %) | 1.00 |
| Current smoking status, yes, n (%) | 1 (2 %) | 0 (0 %) | 1 (5 %) | 0.40 |
| Current alcohol consumption, yes, n (%) | 51 (88 %) | 31 (86 %) | 20 (91 %) | 0.70 |
| Prophylactic bilateral mastectomy, yes, n (%) | 9 (16 %) | 0 (0 %) | 9 (41 %) | <0.001 |
| Prophylactic oophorectomy, yes, n (%) | 14 (24 %) | 1 (3 %) | 13 (59 %) | <0.001 |
| Current hormone replacement therapy, yes, n (%) | 10 (17 %) | 3 (8 %) | 7 (32 %) | 0.03 |
| BMI, kg/m2 (SD) | 24.2 (5) | 24.6 (5) | 23.5 (4) | 0.39 |
| BRCA1 mRNA expression, mean (95 % CI) | 164.3 (155, 173.5) | 175.1 (163.4, 187) | 146.7 (134.2, 159) | 0.002 |