Table 2.
Characteristics of participants in the Nurses’ Health Study cohorts with breast tumor tissue.
| Characteristic | NHS (N = 4,673) | NHS II (N = 1,241) | |
|---|---|---|---|
|
| |||
| Age at diagnosis, mean (SD) | 61.3 (9.0) | 46.5 (5.2) | |
| Gradea, n (%) | Well-differentiated | 938 (23.6) | 152 (15.4) |
| Moderately differentiated | 2144 (53.9) | 540 (54.7) | |
| Poorly/undifferentiated | 894 (22.5) | 296 (30.0) | |
| Missing | 697 | 253 | |
| Tumor size, n (%) | ≤1.0 cm | 1230 (29.9) | 237 (23.9) |
| 1.1 – 2.0 cm | 1611 (39.1) | 412 (41.6) | |
| 2.1 – 4.0 cm | 932 (22.6) | 272 (27.5) | |
| >4.0 cm | 346 (8.4) | 69 (7.0) | |
| Missing or carcinoma in situ | 554 | 251 | |
| Node status, n (%) | Node negative | 3444 (73.7) | 884 (71.8) |
| 1 – 3 nodes positive | 741 (15.9) | 225 (18.3) | |
| 4 – 9 nodes positive | 256 (5.5) | 103 (8.4) | |
| 10+ nodes positive | 157 (3.4) | 17 (1.4) | |
| Metastatic at diagnosis | 75 (1.6) | 3 (0.2) | |
| Missing | 0 | 9 | |
| Stage, n (%) | In situ | 523 (11.7) | 247 (20.3) |
| 1 | 2168 (48.3) | 483 (39.7) | |
| 2 | 1237 (27.6) | 345 (28.4) | |
| 3 | 483 (10.8) | 138 (11.4) | |
| 4 | 75 (1.7) | 3 (0.3) | |
| Missing | 187 | 25 | |
a
Grade was obtained from centralized review of tumor tissue or pathology reports if centralized review was unavailable.
Percentages exclude the number of missing for each variable. Percentages may not add up to 100 due to rounding.