Table 1. Clinical, demographic, and facility factors by receipt of intensity modulated radiation therapy following lumpectomy.
| Variable | IMRT (n = 2580) |
Conventional RT (n = 10457) |
p-value |
|---|---|---|---|
| Age in Years at Index Date, Mean (SD) | 74.5 (5.9) | 74.4 (5.9) | 0.44 |
| n (column %) | |||
| Race | |||
| White/Caucasian | 2319 (89.9%) | 9330 (89.2%) | 0.30 |
| Non-White/Caucasian | 261 (10.1%) | 1127 (10.8%) | |
| Residence | |||
| Big Metro (>1 million people) | 1764 (68.4%) | 5585 (53.4%) | <0.0001 |
| Other Setting (<1 million people) | 816 (31.6%) | 4872 (46.6%) | |
| Charlson Comorbidity Index | |||
| 0 | 916 (35.5%) | 3528 (33.7%) | 0.08 |
| ≥1 | 1664 (64.5%) | 6929 (66.3%) | |
| Laterality | |||
| Left breast | 1552 (60.3%) | 5034 (48.2%) | <0.0001 |
| Right breast | 1021 (39.7%) | 5401 (51.8%) | |
| Tumor Stage | |||
| Stage I | 2019 (78.3%) | 8242 (78.8%) | 0.58 |
| Stage II | 561 (21.7%) | 2215 (21.2%) | |
| Tumor Grade | |||
| 1 | 862 (33.4%) | 3542 (33.9%) | 0.33 |
| 2 | 1236 (47.9%) | 4888 (46.7%) | |
| 3 | 374 (14.5%) | 1626 (15.6%) | |
| SEER Registry | |||
| California | 666 (25.8%) | 3539 (33.8%) | <0.0001 |
| Connecticut | 126 (4.9%) | 757 (7.2%) | |
| Detroit | 392 (15.2%) | 361 (3.5%) | |
| Georgia | 391 (15.2%) | 1088 (10.4%) | |
| Hawaii | 0 (0%) | 125 (1.2%) | |
| Iowa | 24 (0.9%) | 725 (6.9%) | |
| Kentucky | 173 (6.7%) | 548 (5.2%) | |
| Louisiana | 181 (7.0%) | 435 (4.2%) | |
| New Jersey | 522 (20.2%) | 1546 (14.8%) | |
| New Mexico | 39 (1.5%) | 211 (2.0%) | |
| Seattle | 52 (2.0%) | 842 (8.1%) | |
| Utah | 14 (0.5%) | 280 (2.7%) | |
| Facility type | |||
| Hospital-based | 1153 (44.7%) | 7321 (70.0%) | <0.0001 |
| Free-standing center | 1427 (55.3%) | 3136 (30.0%) | |
| LCD status | |||
| Favorable | 666 (25.8%) | 3539 (33.8%) | <0.0001 |
| Neutral | 1809 (70.1%) | 5585 (53.4%) | |
| Unfavorable | 105 (4.1%) | 1333 (12.8%) | |
| Median income in census track | |||
| ≤ $90,000 | 2280 (88.4%) | 8681 (83.0%) | <0.0001 |
| >$90,000 | 300 (11.6%) | 1776 (17.0%) | |
| Poverty in census track | |||
| ≤ 25% living in poverty | 2287 (88.6%) | 9210 (88.1%) | 0.48 |
| >25% living in poverty | 293 (11.4%) | 1247 (11.9%) | |
| Education in census track | |||
| ≤ 50% college educated | 2264 (87.8%) | 8646 (82.7%) | <0.0001 |
| > 50% college educated | 316 (12.3%) | 1811 (17.3%) | |
Note: Bold p-values indicate statistically significant differences between cases and controls at α = 0.05