Table 1.
Characteristics of BRCA mutation carriers with or without a bilateral oophorectomy
| Variable | No oophorectomy (n = 2170) | Oophorectomy (n = 1552) | P* |
|---|---|---|---|
| Year of birth, mean (range) | 1971.3 (1911–1993) | 1957.5 (1908–1982) | <.001 |
| Mean age at oophorectomy† (range), y | N/A | 46.3 (13–78) | N/A |
| Age at baseline | |||
| <30 y, No. (%) | 935 (43.1) | 30 (1.9) | |
| 30–39 y, No. (%) | 738 (34.0) | 359 (23.1) | |
| 40–49 y, No. (%) | 297 (13.7) | 644 (41.5) | |
| ≥50 y, No. (%) | 200 (9.2) | 519 (33.4) | |
| Mean age (range), y | 33.4 (13–85) | 46.2 (21–88) | <.001 |
| Mean follow-up (range), y | 5.45 (0–21.18) | 6.35 (0–19.50) | <.001 |
| Breast cancer | |||
| No, No. (%) | 1963 (90.5) | 1409 (90.8) | |
| Yes, No. (%) | 207 (9.5) | 143 (9.2) | .73 |
| Mean age at diagnosis (range), y | 42.5 (25–75) | 52.5 (33–81) | <.001 |
| BRCA mutation | |||
| BRCA1‡, No. (%) | 1782 (82.8) | 1187 (77.0.0) | |
| BRCA2‡, No. (%) | 370 (17.2) | 355 (23.0) | |
| BRCA1 and BRCA2 or missing, No. | 18 | 10 | <.001 |
| Parity | |||
| Nulliparous, No. (%) | 908 (42.2) | 189 (12.2 ) | |
| 1 child, No. (%) | 440 (20.5) | 217 (14.1) | |
| 2 children, No. (%) | 486 (22.6) | 652 (42.2) | |
| 3 children, No. (%) | 215 (10.0) | 347 (22.5) | |
| ≥4 children, No. (%) | 102 (4.7) | 139 (9.0) | |
| Mean No. children (range) | 1.2 (0–10) | 2.1 (0–8) | <.001 |
| Missing, No. | 19 | 8 | <.001 |
| Breastfeeding | |||
| Never, No. (%) | 1065 (51.7) | 387 (28.7) | |
| Ever, <12 mo, No. (%) | 562 (27.3) | 539 (40.0) | |
| Ever, ≥12 mo, No. (%) | 434 (21.1) | 421 (31.3) | |
| Mean time breastfeeding (range), mo | 6.9 (0–101) | 10.3 (0–14) | <.001 |
| Missing, No. | 109 | 205 | <.001 |
| Oral contraceptive use at baseline | |||
| Never, No. (%) | 852 (39.4) | 506 (32.9) | |
| Ever, No. (%) | 1308 (60.6) | 1031 (67.1) | |
| Missing, No. | 10 | 15 | <.001 |
| Family history of breast cancer§ | |||
| 0, No. (%) | 809 (44.1) | 562 (45.9) | |
| 1, No. (%) | 898 (49.0) | 475 (38.8) | |
| 2, No. (%) | 98 (5.3) | 157 (12.8) | |
| ≥3, No. (%) | 29 (1.6) | 30 (2.5) | <.001 |
| Mean No. family members with breast cancer (range) | 0.6 (0–4) | 0.7 (0–4) | |
| Missing, No. | 336 | 328 | .004 |
| Age at menarche | |||
| ≤11 y, No. (%) | 225 (10.7) | 198 (13.2) | |
| 12 y, No. (%) | 485 (23.1) | 357 (23.8) | |
| 13 y, No. (%) | 615 (29.3) | 404 (26.9) | |
| ≥14 y, No. (%) | 774 (36.9) | 542 (36.1) | |
| Mean age (range) | 13.1 (9–19) | 13.1 (9–28) | .09 |
| Missing, No. | 71 | 51 | .47 |
| Country of residence, No. (%) | |||
| Poland | 1158 (53.4) | 448 (28.9) | |
| Canada | 430 (19.80) | 488 (31.4) | |
| Other | 226 (10.4) | 279 (18.0) | |
| United States | 356 (16.4) | 337 (21.7) | <.001 |
*
P values were calculated using the Student's t test for continuous variables and the chi-square test for categorical variables. All tests were two-sided.
†Oophorectomy refers to bilateral oophorectomy.
‡Women with both a BRCA1 and BRCA2 mutation were coded as missing.
§Number of affected first-degree relatives.