Table 6.
Baseline characteristics for patients receiving regional nodal radiotherapy compared to whole breast radiotherapy only in patients with 1–2 positive nodes who undergo SLNB only
| Demographic or Clinical Characteristics Univariate Analysis (N = 6520) | Whole breast RT (N = 4136, 63.44%) | Breast and nodal RT (N = 2384, 36.56%) | |||
|---|---|---|---|---|---|
| No. | % | No. | % | p Value | |
| Facility Type | 0.0003 | ||||
| Community cancer program | 349 | 56.00 | 274 | 44.00 | |
| Comprehensive community cancer program | 2008 | 63.20 | 1167 | 36.80 | |
| Academic/research program | 1334 | 64.40 | 736 | 35.60 | |
| Other | 445 | 68.30 | 63 | 31.70 | |
| Facility location | <0.0001 | ||||
| New England | 278 | 59.90 | 186 | 40.10 | |
| Middle Atlantic region | 706 | 70.20 | 299 | 29.80 | |
| South Atlantic region | 829 | 60.80 | 534 | 39.20 | |
| East North Central region | 703 | 60.60 | 457 | 39.40 | |
| East South Central region | 182 | 61.50 | 114 | 38.50 | |
| West North Central region | 303 | 62.50 | 182 | 37.50 | |
| West South Central region | 203 | 68.10 | 95 | 31.90 | |
| Mountain region | 219 | 59.70 | 148 | 40.30 | |
| Pacific region | 599 | 66.00 | 303 | 34.00 | |
| Unknown region | 114 | 65.50 | 60 | 34.50 | |
| Age at diagnosis (years) | 0.3651 | ||||
| <40 | 114 | 65.52 | 60 | 34.48 | |
| 40–49 | 665 | 63.09 | 389 | 36.91 | |
| 50–59 | 1174 | 61.99 | 720 | 38.01 | |
| 60–69 | 1303 | 65.28 | 693 | 34.72 | |
| 70–79 | 670 | 62.50 | 402 | 37.50 | |
| ≥80 | 210 | 63.64 | 120 | 36.36 | |
| Race | 0.0029 | ||||
| White | 3203 | 62.70 | 1909 | 37.30 | |
| Black | 369 | 61.20 | 234 | 38.80 | |
| Hispanic | 245 | 70.20 | 104 | 29.80 | |
| Asian/Pacific | 158 | 70.80 | 65 | 29.20 | |
| Other or Unknown | 161 | 69.10 | 72 | 30.90 | |
| Insurance status | 0.4771 | ||||
| Not insured | 84 | 65.12 | 45 | 34.88 | |
| Private insurance | 2280 | 62.60 | 1362 | 37.40 | |
| Medicaid | 256 | 63.68 | 146 | 36.32 | |
| Medicare | 1408 | 64.06 | 790 | 35.94 | |
| Other | 50 | 71.43 | 20 | 28.57 | |
| Median Income | 0.0107 | ||||
| <$38,000 | 568 | 70.00 | 3 | 30.00 | |
| $38,000–$47,999 | 783 | 64.33 | 315 | 35.67 | |
| $48,000–$62,999 | 1084 | 61.27 | 495 | 38.73 | |
| $63,000 + | 1694 | 61.14 | 689 | 38.86 | |
| Unknown | 7 | 70.00 | 3 | 30.00 | |
| Percent with High School degree | 0.079 | ||||
| ≥21% | 533 | 64.92 | 288 | 35.08 | |
| 13–20% | 935 | 61.59 | 583 | 38.41 | |
| 7.0–12.9% | 1342 | 62.19 | 816 | 37.81 | |
| <7% | 1321 | 65.56 | 694 | 34.44 | |
| Unknown | 5 | 62.50 | 3 | 37.50 | |
| Population density | 0.0123 | ||||
| Metro counties | 3570 | 64.12 | 1998 | 35.88 | |
| Urban counties | 421 | 58.47 | 299 | 41.53 | |
| Rural counties | 48 | 62.34 | 29 | 37.66 | |
| Charlson-Deyo Comorbidity Score | 0.3379 | ||||
| 0 | 3464 | 63.10 | 2026 | 36.90 | |
| 1 | 572 | 65.67 | 299 | 34.33 | |
| 2 | 100 | 62.89 | 59 | 37.11 | |
| Year of diagnosis | 0.5852 | ||||
| 2012 | 2071 | 63.76 | 1177 | 36.24 | |
| 2013 | 2065 | 63.11 | 1207 | 36.89 | |
| Laterality | 0.5027 | ||||
| Right | 2061 | 63.14 | 1203 | 36.86 | |
| Left | 2073 | 63.71 | 1181 | 36.29 | |
| Grade | 0.0014 | ||||
| Well differentiated | 984 | 65.82 | 511 | 34.18 | |
| Moderately differentiated | 2025 | 64.37 | 1121 | 35.63 | |
| Poorly differentiated | 850 | 59.73 | 573 | 40.27 | |
| Tumor Size | <.0001 | ||||
| 1–5 mm | 112 | 70.00 | 48 | 30.00 | |
| 6–10 mm | 662 | 69.83 | 286 | 30.17 | |
| 11–20 mm | 2151 | 63.83 | 1219 | 36.17 | |
| 21–50 mm | 1189 | 59.45 | 811 | 40.55 | |
| Regional Nodes Positive | <.0001 | ||||
| 1 | 3701 | 65.77 | 1926 | 34.23 | |
| 2 | 435 | 48.71 | 458 | 51.29 | |
| Clinical T-Stage | <.0001 | ||||
| T1 | 2999 | 65.07 | 1610 | 34.93 | |
| T2 | 870 | 58.78 | 610 | 41.22 | |
| Pathologic T-Stage | <.0001 | ||||
| T1 | 2844 | 65.04 | 1529 | 34.96 | |
| T2 | 1209 | 59.62 | 819 | 40.38 | |
| Lymphovascular Invasion | 0.0797 | ||||
| Absent | 2333 | 63.94 | 1316 | 36.06 | |
| Present | 1246 | 61.59 | 777 | 38.41 | |
| Hormone receptor subtype | 0.078 | ||||
| Hormone receptor positive and HER2+ | 182 | 59.48 | 124 | 40.52 | |
| Hormone receptor positive and HER2− | 3582 | 64.06 | 2010 | 35.94 | |
| Hormone receptor positive and HER2 borderline | 61 | 66.30 | 31 | 33.70 | |
| Hormone receptor negative | 3 | 75.00 | 1 | 25.00 | |
| HER2+ | 79 | 62.20 | 48 | 37.80 | |
| Hormone receptor negative and HER2 borderline | 3 | 60.00 | 2 | 40.00 | |
| Triple negative | 215 | 56.58 | 165 | 43.42 | |
| Surgical Margins | 0.7915 | ||||
| Negative | 3959 | 63.43 | 2283 | 6.57 | |
| Positive | 167 | 64.23 | 93 | 35.77 | |
| Radiation Technique | 0.1031 | ||||
| Conformal or 3-D Therapy | 376 | 56.04 | 295 | 43.96 | |
| IMRT | 158 | 61.96 | 97 | 38.04 | |
| Receipt of Chemotherapy | <.0001 | ||||
| None | 2011 | 66.26 | 1024 | 33.74 | |
| Chemotherapy given | 2067 | 60.78 | 1334 | 39.22 | |
| Receipt of Endocrine Therapy | 0.0386 | ||||
| None | 470 | 60.03 | 313 | 39.97 | |
| Endocrine therapy given | 3589 | 63.83 | 2034 | 36.17 |