Table 1.
Baseline characteristics according to lymph node status in 1411 cT1-2 breast cancer patients from 7 Dutch hospitals operated between 2000 and 2003
| Characteristic | Lymph node status | P | |||
|---|---|---|---|---|---|
| pN0 (n = 922) | pN1micro (n = 103) | pN1a (n = 285) | pN≥1b (n = 101) | ||
| Accrued years of follow-up | 5720 | 642 | 1733 | 582 | |
| Age (years)a | 58.2 (27.4–89.5) | 55.9 (34.9–83.1) | 54.0 (32.7–90.7) | 51.8 (29.6–84.7) | <.001c |
| Age (%) | |||||
| <35 years | 2.1% | 1.0% | 1.1% | 4.0% | |
| 35–49 years | 21.7% | 28.2% | 33.7% | 38.6% | |
| ≥50 years | 76.2% | 70.9% | 65.3% | 57.4% | <.001e |
| Tumor size (cm)b | 1.7 (0.9) | 2.0 (0.9) | 2.2 (1.0) | 2.7 (1.5) | <.001d |
| Tumor size (%) | |||||
| <1 cm | 14.6% | 3.9% | 6.0% | 2.0% | |
| 1–2 cm | 53.6% | 52.4% | 39.3% | 28.7% | |
| 2–3 cm | 24.0% | 33.0% | 37.2% | 40.6% | |
| ≥3 cm | 7.8% | 10.7% | 17.5% | 28.7% | <.001e |
| Bloom-Richardson grade (%) | |||||
| Well differentiated | 18.8% | 15.5% | 13.3% | 9.9% | |
| Moderately differentiated | 54.8% | 69.9% | 64.2% | 53.5% | |
| Poorly differentiated | 26.5% | 14.6% | 22.5% | 36.6% | <.001e |
| Mitotic activity indexa | 6 (0–102) | 6 (0–25) | 10 (0–72) | 10 (0–71) | <.001c |
| Mitotic activity index (%) | |||||
| <10 | 64.1% | 70.9% | 49.8% | 46.5% | |
| ≥10 | 35.9% | 29.1% | 50.2% | 53.5% | <.001e |
| Estrogen receptor positive (%) | 79.2% | 81.6% | 80.4% | 78.2% | .91e |
| Progesterone receptor positive (%) | 67.7% | 75.7% | 76.5% | 67.3% | .02e |
| HER2/neu positive (%) | 16.0% | 5.9% | 18.0% | 42.9% | .004e |
Records with missing values that were imputed (see supplementary appendix): tumor size: 8 (<1%); Bloom-Richardson grade: 350 (25%); mitotic activity index: 505 (36%); estrogen receptor status: 41 (3%); progesterone receptor status: 55 (4%). For 1215 records HER2/neu status was unknown, these values were not imputed (shown here are the results from 196 records)
Percentages may not total 100% due to rounding
aMedian (range)
bMean (standard deviation)
cKruskall-Wallis test
dOne-way ANOVA test
eChi-square test