Table 1.
Demographic, Disease, and Treatment Characteristics According to Histologic Subtype
| Characteristic | Histologic Subtype (N = 2,923) |
Fisher's Exact P | |||
|---|---|---|---|---|---|
| Ductal (n = 2,599) |
Lobular (n = 324) |
||||
| No. | % | No. | % | ||
| Chemotherapy strata | .01 | ||||
| No chemotherapy | 2,059 | 79.2 | 237 | 73.1 | |
| Received chemotherapy | 540 | 20.8 | 87 | 26.9 | |
| Random assignment strata | .001 | ||||
| 4-arm | 1,880 | 72.3 | 262 | 80.9 | |
| 2-arm | 719 | 27.7 | 62 | 19.1 | |
| Subtype | < .001 | ||||
| Lum A | 1,436 | 55.3 | 237 | 73.1 | |
| Lum B | 1,163 | 44.7 | 87 | 26.9 | |
| Age, years | .19 | ||||
| ≤ 55 | 584 | 22.5 | 86 | 26.5 | |
| 56-70 | 1,638 | 63.0 | 199 | 61.4 | |
| ≥ 71 | 377 | 14.5 | 39 | 12.0 | |
| Obese (BMI ≥ 30 kg/m2) | .93 | ||||
| No | 1,929 | 74.2 | 243 | 75.0 | |
| Yes | 561 | 21.6 | 67 | 20.7 | |
| Unknown | 109 | 4.2 | 14 | 4.3 | |
| Nodal status | .29 | ||||
| Nx/N0 | 1,473 | 56.7 | 178 | 54.9 | |
| N1-N3 | 709 | 27.3 | 83 | 25.6 | |
| ≥ N4 | 417 | 16.0 | 63 | 19.4 | |
| Tumor size, cm | < .001 | ||||
| < 2 | 1,685 | 64.8 | 158 | 48.8 | |
| ≥ 2 | 905 | 34.8 | 162 | 50.0 | |
| Missing | 9 | 0.3 | 4 | 1.2 | |
| Tumor grade (centrally assessed) | < .001 | ||||
| 1 | 553 | 21.3 | 13 | 4.0 | |
| 2 | 1,443 | 55.5 | 309 | 95.4 | |
| 3 | 589 | 22.7 | 2 | 0.6 | |
| Missing | 14 | 0.5 | — | — | |
| Peritumoral invasion (centrally assessed) | < .001 | ||||
| No | 2,304 | 88.6 | 317 | 97.8 | |
| Yes | 285 | 11.0 | 7 | 2.2 | |
| Missing | 10 | 0.4 | — | — | |
| Treatment assigned | .32 | ||||
| Letrozole | 1,300 | 50.0 | 152 | 46.9 | |
| Tamoxifen | 1,299 | 50.0 | 172 | 53.1 | |
| Local therapy | < .001 | ||||
| LTM/RT | 1,426 | 54.9 | 145 | 44.8 | |
| LTM/no RT | 85 | 3.3 | 4 | 1.2 | |
| Mastectomy/RT | 423 | 16.3 | 86 | 26.5 | |
| Mastectomy/no RT | 663 | 25.5 | 88 | 27.2 | |
| Other | 2 | 0.1 | 1 | 0.3 | |
Abbreviations: BMI, body mass index; LTM: less than mastectomy; Lum A, luminal A; Lum B, luminal B; RT, radiotherapy.