Table 2.
Patient demographic and clinical characteristics.
| Variables | Before PSM | After PSM | ||||
|---|---|---|---|---|---|---|
| Non-PMRT | PMRT | p | Non-PMRT | PMRT | p | |
| N = 2160 | N = 1588 | N = 1264 | N = 1264 | |||
| Age, years | <0.001 | 0.485 | ||||
| 20–30 | 20 (0.9) | 23 (1.4) | 16 (1.3) | 13 (1.0) | ||
| 31–40 | 103 (4.8) | 106 (6.7) | 73 (5.8) | 79 (6.3) | ||
| 41–50 | 292 (13.5) | 261 (16.4) | 196 (15.5) | 181 (14.3) | ||
| 51–60 | 459 (21.3) | 402 (25.3) | 289 (22.9) | 322 (25.5) | ||
| 61–70 | 537 (24.9) | 392 (24.7) | 326 (25.8) | 319 (25.2) | ||
| 71–80 | 465 (21.5) | 271 (17.1) | 255 (20.2) | 227 (18.0) | ||
| 81–90 | 284 (13.1) | 133 (8.4) | 109 (8.6) | 123 (9.7) | ||
| Follow-up, months [median] | 39 (1–191) | 49 (1–190) | <0.001 | 41 (1–191) | 51 (1–190) | <0.001 |
| Race/ethnicity | 0.037 | 0.781 | ||||
| Blank | 331 (15.3) | 288 (18.1) | 211 (16.7) | 195 (15.4) | ||
| White | 1659 (76.8) | 1191 (75.0) | 979 (77.5) | 994 (78.6) | ||
| Asian or Pacific Islander | 152 (7.0) | 90 (5.7) | 66 (5.2) | 65 (5.1) | ||
| American Indian/Alaska Native | 13 (0.6) | 10 (0.6) | 8 (0.6) | 8 (0.6) | ||
| Unknown | 5 (0.2) | 9 (0.5) | – | – | ||
| Insurance status | 0.218 | 0.262 | ||||
| Medicaid | 218 (10.1) | 135 (8.5) | 129 (10.2) | 106 (8.4) | ||
| Insured | 1246 (57.7) | 946 (59.6) | 753 (59.6) | 758 (60.0) | ||
| Uninsured/unknown | 696 (32.2) | 507 (31.9) | 382 (30.2) | 400 (31.6) | ||
| Histopathological subtypes | 0.669 | 0.957 | ||||
| Metaplastic | 1,765 (81.7) | 1,321 (83.2) | 1,071 (84.7) | 1,065 (84.3) | ||
| Adenosquamous | 173 (8.0) | 117 (7.4) | 87 (6.9) | 87 (6.9) | ||
| Carcinosarcoma | 123 (5.7) | 91 (5.7) | 63 (5.0) | 63 (5.0) | ||
| Adenospindle/cartilaginous/osseus | 69 (3.2) | 41 (2.6) | 31 (2.5) | 33 (2.6) | ||
| Epithelial/myoepithelial | 30 (1.4) | 18 (1.1) | 12 (0.9) | 16 (1.3) | ||
| Tumor grade | 0.558 | 0.775 | ||||
| Well differentiated | 86 (4.0) | 67 (4.2) | 46 (3.6) | 48 (3.8) | ||
| Moderately differentiated | 245 (11.3) | 188 (11.8) | 137 (10.8) | 148 (11.7) | ||
| Poorly differentiated | 1427 (66.1) | 1,068 (67.3) | 860 (68.0) | 868 (68.7) | ||
| Undifferentiated | 100 (4.6) | 73 (4.6) | 52 (4.1) | 52 (4.1) | ||
| Unknown | 302 (14.0) | 192 (12.1) | 169 (13.4) | 148 (11.7) | ||
| Tumor size | 0.142 | 0.061 | ||||
| ≤10 mm | 106 (4.9) | 105 (6.6) | 52 (4.1) | 91 (7.2) | ||
| ≤20 mm | 373 (17.3) | 314 (19.8) | 232 (18.4) | 275 (21.8) | ||
| ≤30 mm | 794 (36.8) | 511 (32.2) | 464 (36.7) | 415 (32.8) | ||
| ≤40 mm | 311 (14.4) | 197 (12.4) | 200 (15.8) | 171 (13.5) | ||
| ≤50 mm | 189 (8.8) | 132 (8.3) | 203 (16.1) | 218 (17.2) | ||
| >50 mm | 387 (17.9) | 329 (20.7) | ||||
| Lymph node | <0.001 | 0.419 | ||||
| 0 | 1,463 (67.7) | 1,150 (72.4) | 1,028 (81.3) | 1,013 (80.1) | ||
| 1–3 | 276 (12.8) | 223 (14.0) | 169 (13.4) | 165 (13.1) | ||
| 4–9 | 76 (3.5) | 75 (4.7) | 45 (3.6) | 54 (4.3) | ||
| ≥10 | 345 (16.0) | 140 (8.8) | 22 (1.7) | 32 (2.5) | ||
| Risk stratification | <0.001 | <0.001 | ||||
| Low risk | 482 (22.3) | 402 (25.3) | 284 (22.5) | 352 (27.8) | ||
| Intermediate risk | 1,208 (55.9) | 841 (53.0) | 727 (57.5) | 666 (52.7) | ||
| High risk | 257 (11.9) | 256 (16.1) | 143 (11.3) | 175 (13.8) | ||
| Others | 213 (9.9) | 89 (302) | 110 (8.7) | 71 (5.6) | ||
| ER status | <0.001 | 0.253 | ||||
| Negative | 1,629 (75.4) | 1,230 (77.5) | 1,021 (80.8) | 1,003 (79.4) | ||
| Positive | 355 (16.4) | 291 (18.3) | 184 (14.6) | 211 (16.7) | ||
| Unknown | 176 (8.1) | 67 (4.2) | 59 (4.7) | 50 (4.0) | ||
| PR status | <0.001 | 0.166 | ||||
| Negative | 1,743 (80.7) | 1,310 (82.5) | 1,074 (85.0) | 1,052 (83.2) | ||
| Positive | 235 (10.9) | 205 (12.9) | 128 (10.1) | 157 (12.4) | ||
| Unknown | 182 (8.4) | 73 (4.6) | 62 (4.9) | 55 (4.4) | ||
| Treatment with chemotherapy | <0.001 | 0.966 | ||||
| Yes | 1,078 (49.9) | 1,164 (73.3) | 874 (69.1) | 873 (69.1) | ||
| No | 1,082 (50.1) | 424 (26.7) | 390 (30.9) | 391 (30.9) | ||
MBC, metaplastic breast cancer; ER, estrogen receptor; PR, progesterone receptor; PSM, propensity score matching; PMRT, post-mastectomy radiotherapy.
According to the pathological stage of lymph nodes, we divided lymph node state into four groups by the number of lymph node metastasis.