Table 1.
Sample characteristics
| Characteristic | Total (%) (N = 1778) | % | Radiotherapy (n = 1405) |
No radiotherapy (n = 373) |
P* | ||
|---|---|---|---|---|---|---|---|
| No. | Col % | No. | Col % | ||||
| Mean age (SD), y | 1778 | 59 (9) | 1405 | 58 (9) | 373 | 63 (9) | <.001 |
| Age at random assignment/enrollment | |||||||
| <60 years | 903 | 50.8 | 773 | 55.1 | 130 | 34.8 | <.001 |
| 60-70 years | 296 | 16.6 | 174 | 12.3 | 122 | 32.7 | |
| >70 years | 579 | 32.6 | 458 | 32.6 | 121 | 32.5 | |
| Tumor grade | |||||||
| Low | 439 | 24.7 | 341 | 24.3 | 98 | 26.3 | <.001 |
| Intermediate | 765 | 43.0 | 610 | 43.4 | 155 | 41.6 | |
| High | 157 | 8.8 | 121 | 8.6 | 36 | 9.6 | |
| Missing/Unknown | 417 | 23.5 | 333 | 23.7 | 84 | 22.5 | |
| Pathological tumor size, cm | |||||||
| ≤ 1 | 518 | 29.1 | 357 | 25.4 | 161 | 43.1 | <.001 |
| >1 | 1005 | 56.5 | 904 | 64.3 | 101 | 27.1 | |
| Unknown (but stage I or ≤2 cm per protocol) | 255 | 14.4 | 144 | 10.3 | 111 | 29.8 | |
| Hormone status | |||||||
| ER+ and PR+ | 1361 | 76.5 | 1143 | 81.3 | 218 | 58.4 | <.001 |
| Other (ER+ or PR+ or one unknown and the other +) | 417 | 23.5 | 262 | 18.7 | 155 | 41.6 | |
| HER2 status | |||||||
| Known negative | 986 | 55.5 | 835 | 59.5 | 151 | 40.5 | <.001 |
| Unknown | 792 | 44.5 | 570 | 40.5 | 222 | 59.5 | |
| Initial endocrine therapy | |||||||
| Tamoxifen | 1145 | 64.4 | 815 | 58 | 330 | 88.5 | <.001 |
| AI† | 434 | 24.4 | 403 | 28.7 | 31 | 8.3 | |
| AI and Tamoxifen | 161 | 9.1 | 152 | 10.9 | 9 | 2.4 | |
| Ovarian suppression (+/- AI or Tam) | 38 | 2.1 | 35 | 2.5 | 3 | 0.8 | |
| Study | |||||||
| NSABP B-21 | 216 | 12.2 | 103 | 7.4 | 113 | 30.3 | <.001 |
| CALGB 9343 | 135 | 7.6 | 68 | 4.8 | 67 | 17.9 | |
| Toronto/Vancouver Trial | 177 | 10 | 87 | 6.2 | 90 | 24.1 | |
| GBSG V | 88 | 4.9 | 46 | 3.3 | 42 | 11.3 | |
| TAILORx | 809 | 45.5 | 748 | 53.2 | 61 | 16.4 | |
| NSABP B-14 | 208 | 11.7 | 208 | 14.8 | −‡ | −‡ | |
| NSABP B-20 | 145 | 8.1 | 145 | 10.3 | −‡ | −‡ | |
| Years of diagnosis | |||||||
| 1980-1989 | 353 | 19.8 | 353 | 25.1 | −‡ | −‡ | <.001 |
| 1990-2000 | 616 | 34.7 | 304 | 21.7 | 312 | 83.7 | |
| 2001 or later | 809 | 45.5 | 748 | 53.2 | 61 | 16.3 | |
| Overall median length of follow-up (range), y | 1778 | 5(0.1–23) | 1405 | 5(0.1–23) | 373 | 8(0.2–18) | <.001 |
| Radiotherapy randomized | |||||||
| Yes | 616 | 34.7 | 304 | 21.6 | 312 | 83.7 | <.001 |
| No | 1162 | 65.3 | 1101 | 78.4 | 61 | 16.3 | |
| Oncotype DX risk group | |||||||
| 0-10 | 1120 | 63.0 | 959 | 68.3 | 161 | 43.1 | <.001 |
| 11-18 | 658 | 37.0 | 446 | 31.7 | 212 | 56.9 | |
*
Two-sided P values are based on χ2 or Student t tests. ER = estrogen receptor; PR = progesterone receptor; AI = aromatase inhibitor; NSABP = National Surgical Adjuvant Breast and Bowel Project; CALGB = Cancer And Leukemia Group B; TAILORx = Trial Assigning IndividuaLized Options for Treatment (Rx); GBSG V = German Breast Cancer Study Group V.
†
Approximately 20% women younger than age 60 years and 30% women aged 60 years and older received aromatase inhibitors only.
‡
Radiotherapy was given to women per treatment protocol. Assumed 100% compliance to protocol.