Table 2 Study population and tumor characteristics by ER status in the NHS and the NHSII
|  | ER+ tumors N = 471 | ER- tumors N = 127 | ||
|---|---|---|---|---|
| Â | Mean | SD | Mean | SD |
Age at diagnosis, years | 61.4 | 9.6 | 59.1 | 8.9 |
BMI at diagnosis, kg/m2 | 26.0 | 5.0 | 26.1 | 5.1 |
Parity | 2.6 | 1.8 | 2.9 | 1.8 |
Recent alcohol, g/day | 6.5 | 11.7 | 5.8 | 10.0 |
Cumulative average alcohol, g/day | 6.4 | 9.5 | 5.5 | 8.2 |
| Â | N | % | N | % |
First-degree family history | 79 | 16.8 | 16 | 12.6 |
Year of diagnosis | ||||
 1990‒1999 | 251 | 53.3 | 91 | 71.7 |
 2000 − 2004 | 182 | 38.6 | 26 | 20.5 |
 2005‒2009 | 38 | 8.1 | 10 | 7.9 |
Tumor size | ||||
 0.1‒2.0 cm | 365 | 77.5 | 68 | 53.5 |
 2.1‒4.0 cm | 75 | 15.9 | 46 | 36.2 |
 > 4.0 cm | 23 | 4.9 | 7 | 5.5 |
 Unknown | 8 | 1.7 | 6 | 4.7 |
Lymph node involvement | ||||
 None | 349 | 74.1 | 95 | 74.8 |
 1‒3 positive nodes | 85 | 18.0 | 22 | 17.3 |
 > 3 positive nodes | 33 | 7.0 | 8 | 6.3 |
 Metastatic at diagnosis | 4 | 0.8 | 1 | 0.8 |
 Unknown | 0 | 0 | 1 | 0.8 |
Grade | ||||
 Well-differentiated | 124 | 26.3 | 6 | 4.7 |
 Moderately differentiated | 243 | 51.6 | 35 | 27.6 |
 Poorly differentiated | 89 | 18.9 | 67 | 52.8 |
 Unknown | 15 | 3.2 | 19 | 15.0 |
Stagea | ||||
 I | 305 | 64.8 | 57 | 44.9 |
 II | 122 | 25.9 | 59 | 46.5 |
 III | 40 | 8.5 | 9 | 7.1 |
 IV | 4 | 0.8 | 1 | 0.8 |
 Unknown | 0 | 0 | 1 | 0.8 |