Table 1.
Selected characteristics of the study population by menopausal status and case status (Nurses’ Health Study, 1989–2006)
| Population characteristics | Premenopausal (168 cases/765 controls) | Postmenopausal (577 cases/1689 controls) | ||
|---|---|---|---|---|
| Mean (SD) | Mean (SD) | |||
| Age at blood collection* | 49.5 (3.8) | 49.6 (3.5) | 62.7 (6.5) | 62.7 (6.3) |
| Age at menarche | 12.3 (1.4) | 12.4 (1.3) | 12.5 (1.4) | 12.6 (1.4) |
| BMI at blood collection | 24.7 (4.0) | 25.5 (4.7) | 26.0 (4.7) | 25.8 (4.5) |
| Prolactin (ng/mL) | 15.1 (9.2) | 14.3 (8.8) | 12.0 (7.7) | 11.4 (7.7) |
| Breastfeeding (months) | 9.1 (12.0) | 7.6 (10.9) | 7.1 (10.9) | 5.7 (9.3) |
| Time from blood collection to diagnosis (years) | 6.0 (3.0) | 4.7 (3.1) | ||
| N (%) | N (%) | |||
|---|---|---|---|---|
| Fasting at blood collection* | 106 (63.1) | 481 (62.9) | 411 (71.2) | 1205 (71.3) |
| Family history of breast cancer | 18 (10.7) | 63 (8.2) | 99 (17.2) | 224 (13.3) |
| Parity | ||||
| Nulliparous | 12 (7.1) | 45 (5.9) | 37 (6.4) | 103 (6.1) |
| 1 child | 12 (7.1) | 50 (6.5) | 37 (6.4) | 105 (6.2) |
| 2 children | 52 (31.0) | 267 (34.9) | 143 (24.8) | 372 (22.0) |
| 3 children | 57 (33.9) | 243 (31.8) | 168 (29.1) | 466 (27.6) |
| 4 or more children | 35 (20.8) | 160 (20.9) | 192 (33.3) | 643 (38.1) |
| History of BBD | ||||
| Biopsy-confirmed | 37 (22.0) | 124 (16.2) | 124 (21.5) | 276 (16.3) |
| Unconfirmed or confirmation unknown | 64 (38.1) | 251 (32.8) | 188 (32.6) | 485 (28.7) |
| HT use at blood collection* | – | – | 344 (59.6) | 721 (42.7) |
| Invasive status | ||||
| Invasive | 140 (83.3) | 494 (85.6) | ||
| DCIS | 28 (16.7) | 83 (14.4) | ||
| ER status | ||||
| Negative | 30 (17.9) | 103 (17.9) | ||
| Positive | 137 (81.5) | 462 (80.1) | ||
| Unknown | 1 (0.6) | 12 (2.1) | ||
| PR status | ||||
| Negative | 44 (26.2) | 148 (25.6) | ||
| Positive | 124 (73.8) | 422 (73.1) | ||
| Unknown | – | 7 (1.2) | ||
| HER-2 status | ||||
| Negative | 110 (65.5) | 433 (75.0) | ||
| Positive | 54 (32.1) | 127 (22.0) | ||
| Unknown | 4 (2.4) | 17 (2.9) | ||
| Tumor marker (score) | ||||
| PRLR nuclear | ||||
| Negative (0/1) | 134 (79.8) | 406 (70.4) | ||
| Positive (2/3) | 29 (17.3) | 139 (24.1) | ||
| Unknown | 5 (3.0) | 32 (5.5) | ||
| PRLR cytoplasmic | ||||
| Negative (0/1) | 128 (76.2) | 416 (72.1) | ||
| Positive (2/3) | 35 (20.8) | 129 (22.4) | ||
| Unknown | 5 (3.0) | 32 (5.5) | ||
| pSTAT5 nuclear | ||||
| Negative (0/1) | 117 (69.6) | 394 (68.3) | ||
| Positive (2/3) | 35 (20.8) | 125 (21.7) | ||
| Unknown | 16 (9.5) | 58 (10.1) | ||
| pSTAT5 cytoplasmic | ||||
| Negative (0) | 61 (36.3) | 213 (36.9) | ||
| Positive (1/2) | 91 (54.2) | 306 (53.0) | ||
| Unknown | 16 (9.5) | 58 (10.1) | ||
| pJAK2 | ||||
| Negative (0) | 20 (11.9) | 95 (16.5) | ||
| Positive (1/2) | 127 (75.6) | 409 (70.9) | ||
| Unknown | 21 (12.5) | 73 (12.7) | ||
BMI body mass index, BBD benign breast disease, DCIS ductal carcinoma in situ, HT hormone therapy
*Matching factor; cases who were not using HT at blood collection were matched to two controls and cases using HT at blood collection were matched to one control