TABLE 3.
Factors associated with change in partial breast irradiation eligibility and regional nodal irradiation post-sentinel lymph node biopsy
*p-value was not calculated due to small cell counts
†1401 patients had an Oncotype DX score available
PBI partial breast irradiation, RNI regional nodal irradiation, IDC invasive ductal carcinoma, ILC invasive lobular carcinoma
| Characteristic | Remained PBI eligible (n = 1478) |
Became PBI ineligible post-SLNB (n = 227) |
p-value | No RNI (n = 1728) |
RNI (n = 58) |
p-value |
|---|---|---|---|---|---|---|
| Median age at surgery | 62 | 61 | 0.02 | 62 | 65 | 0.3 |
| Tumor size | <0.001 | * | ||||
| < 5 mm | 233 (98%) | 5 (2%) | 240 (100%) | 0 | ||
| 6-10 mm | 483 (91%) | 48 (9%) | 529 (99.4%) | 3 (0.6%) | ||
| 11-20 mm | 601 (84%) | 115 (16%) | 693 (96%) | 29 (4%) | ||
| 21-30 mm | 161 (73%) | 59 (27%) | 205 (93%) | 16 (7%) | ||
| 31-50 mm | 0 | 0 | 56 (85%) | 10 (15%) | ||
| > 50 mm | 0 | 0 | 5 (100%) | 0 | ||
| Tumor differentiation | <0.001 | <0.001 | ||||
| Well | 346 (92%) | 29 (8%) | 379 (99%) | 2 (0.5%) | ||
| Moderately | 906 (86%) | 152 (14%) | 1060 (96%) | 39 (4%) | ||
| Poorly | 226 (83%) | 46 (17%) | 289 (94%) | 17 (6%) | ||
| Histology | 0.7 | 0.008 | ||||
| IDC | 1180 (86%) | 187 (14%) | 1370 (96%) | 51 (4%) | ||
| ILC | 190 (90%) | 21 (10%) | 229 (99.6%) | 1 (0.4%) | ||
| Mixed | 72 (81%) | 17 (19%) | 90 (94%) | 6 (6%) | ||
| Other | 36 (95%) | 2 (5%) | 39 (100%) | 0 | ||
| Oncotype DX Recurrence Score† | >0.9 | 0.8 | ||||
| ≤ 25 | 1050 (91%) | 99 (9%) | 1171 (99%) | 11 (1%) | ||
| > 25 | 195 (91%) | 19 (9%) | 218 (99.5%) | 1 (0.5%) |