Table 1.
Characteristics of the Patients at Baseline, According to Recurrence-Score Cohort.*
| Characteristic | Recurrence Score, 0–10 (N = 1626) |
Recurrence Score, 11–25 (N = 6897) |
P Value |
|---|---|---|---|
| Percent of all enrolled patients | 15.9 | 67.3 | — |
| Age | |||
| Median (interquartile range) — yr | 58 (50–64) | 55 (48–62) | <0.001 |
| Mean — yr | 57±9 | 55±9 | <0.001 |
| Distribution — no. (%) | <0.001 | ||
| ≤40 yr | 58 (4) | 319 (5) | |
| 41–50 yr | 372 (23) | 1964 (28) | |
| 51–60 yr | 566 (35) | 2503 (36) | |
| 61–70 yr | 519 (32) | 1811 (26) | |
| >70 yr | 111 (7) | 300 (4) | |
| Menopausal status — no./total no. (%) | <0.001 | ||
| Postmenopausal | 1143/1623 (70) | 4396/6873 (64) | |
| Premenopausal | 480/1623 (30) | 2477/6873 (36) | |
| Tumor size in the greatest dimension | |||
| Median (interquartile range) — cm | 1.5 (1.2–2.0) | 1.5 (1.2–2.0) | 0.31 |
| Mean — cm | 1.74±0.77 | 1.71±0.79 | 0.23 |
| Distribution — no./total no. (%) | 0.42 | ||
| <1.0 cm | 128/1626 (8) | 568/6883 (8) | |
| 1.0–1.9 cm | 993/1626 (61) | 4270/6883 (62) | |
| 2.0–2.9 cm | 366/1626 (23) | 1543/6883 (22) | |
| 3.0–3.9 cm | 104/1626 (6) | 358/6883 (5) | |
| ≥4.0 cm | 35/1626 (2) | 144/6883 (2) | |
| Histologic grade of tumor — no./total no. (%) | <0.001 | ||
| Low | 530/1578 (34) | 1941/6665 (29) | |
| Intermediate | 937/1578 (59) | 3812/6665 (57) | |
| High | 111/1578 (7) | 912/6665 (14) | |
| Estrogen-receptor expression — no./total no. (%) | 0.28 | ||
| Negative | 5/1626 (<1) | 10/6885 (<1) | |
| Positive | 1621/1626 (>99) | 6875/6885 (>99) | |
| Progesterone-receptor expression — no./total no. (%) | <0.001 | ||
| Negative | 28/1590 (2) | 528/6752 (8) | |
| Positive | 1562/1590 (98) | 6224/6752 (92) | |
| Primary surgery — no./total no. (%) | <0.001 | ||
| Lumpectomy | 1106/1626 (68) | 4986/6885 (72) | |
| Mastectomy | 520/1626 (32) | 1899/6885 (28) |
Plus–minus values are means ±SD. Patients were assigned to a risk cohort on the basis of the recurrence score on the 21-gene assay. Scores range from 0 to 100, with higher scores indicating a greater risk of recurrence. Patients with a score of 0 to 10 were included in the low-risk cohort and were assigned to receive endocrine therapy alone. Patients with a score of 11 to 25 were included in the midrange-risk cohort and were randomly assigned to receive either chemotherapy plus endocrine therapy or endocrine therapy alone. (Patients with a score of ≥26 were assigned to receive chemotherapy plus endocrine therapy and were not included in this analysis.) Statistical comparisons were calculated with the use of the chi-square test for categorical variables and the Wilcoxon test and Student’s t-test for continuous variables. Tumor size in the greatest dimension, histologic grade of the tumor, and expression of estrogen receptor, progesterone receptor, and HER2 were determined locally and reported by the participating site. Percentages may not total 100 because of rounding.