TABLE 1.
Characteristics of female patients diagnosed with primary T1-T2N0M0 breast cancer in Surveillance, Epidemiology, and End Results (SEER) database.
| Variables | Before propensity score matching, n (%) |
After propensity score matching, n (%) |
||||||
| Overall | IORT | EBRT | P-value | Overall | IORT | EBRT | P-value | |
| Age | <0.001 | 0.925 | ||||||
| ≤45 | 26372 (9.7) | 70 (2.5) | 26302 (9.8) | 288 (2.6) | 70 (2.5) | 218 (2.6) | ||
| 46–65 | 145687 (53.8) | 1347 (49.0) | 144340 (53.8) | 5407 (49.2) | 1347 (49.0) | 4060 (49.3) | ||
| >65 | 98783 (36.5) | 1332 (48.5) | 97451 (36.3) | 5297 (48.2) | 1332 (48.5) | 3965 (48.1) | ||
| Year | <0.001 | 0.998 | ||||||
| 2000–2004 | 60676 (22.4) | 129 (4.7) | 60547 (22.6) | 523 (4.8) | 129 (4.7) | 394 (4.8) | ||
| 2005–2009 | 66274 (24.5) | 96 (3.5) | 66178 (24.7) | 383 (3.5) | 96 (3.5) | 287 (3.5) | ||
| 2010–2013 | 57785 (21.3) | 622 (22.6) | 57163 (21.3) | 2479 (22.6) | 622 (22.6) | 1857 (22.5) | ||
| 2014–2018 | 86107 (31.8) | 1902 (69.2) | 84205 (31.4) | 7607 (69.2) | 1902 (69.2) | 5705 (69.2) | ||
| Marital status | <0.001 | 0.920 | ||||||
| Married | 163126 (60.2) | 1608 (58.5) | 161518 (60.2) | 6458 (58.8) | 1608 (58.5) | 4850 (58.8) | ||
| Single | 33083 (12.2) | 441 (16.0) | 32642 (12.2) | 1752 (15.9) | 441 (16.0) | 1311 (15.9) | ||
| DSW | 64857 (23.9) | 610 (22.2) | 64247 (24.0) | 2443 (22.2) | 610 (22.2) | 1833 (22.2) | ||
| Unknown | 9776 (3.6) | 90 (3.3) | 9686 (3.6) | 339 (3.1) | 90 (3.3) | 249 (3.0) | ||
| Race | <0.001 | 0.552 | ||||||
| White | 223987 (82.7) | 2250 (81.8) | 221737 (82.7) | 9030 (82.2) | 2250 (81.8) | 6780 (82.3) | ||
| African American | 23443 (8.7) | 196 (7.1) | 23247 (8.7) | 789 (7.2) | 196 (7.1) | 593 (7.2) | ||
| Other | 22288 (8.2) | 277 (10.1) | 22011 (8.2) | 1091 (9.9) | 277 (10.1) | 814 (9.9) | ||
| Unknown | 1124 (0.4) | 26 (0.9) | 1098 (0.4) | 82 (0.7) | 26 (0.9) | 56 (0.7) | ||
| Histology | <0.001 | 0.963 | ||||||
| Ductal carcinoma | 205702 (75.9) | 2189 (79.6) | 203513 (75.9) | 8734 (79.5) | 2189 (79.6) | 6545 (79.4) | ||
| Lobular carcinoma | 35380 (13.1) | 285 (10.4) | 35095 (13.1) | 1145 (10.4) | 285 (10.4) | 860 (10.4) | ||
| Other | 29760 (11.0) | 275 (10.0) | 29485 (11.0) | 1113 (10.1) | 275 (10.0) | 838 (10.2) | ||
| Grade | <0.001 | 0.791 | ||||||
| I | 79999 (29.5) | 1109 (40.3) | 78890 (29.4) | 4453 (40.5) | 1109 (40.3) | 3344 (40.6) | ||
| II | 114190 (42.2) | 1255 (45.7) | 112935 (42.1) | 5032 (45.8) | 1255 (45.7) | 3777 (45.8) | ||
| III | 63358 (23.4) | 344 (12.5) | 63014 (23.5) | 1356 (12.3) | 344 (12.5) | 1012 (12.3) | ||
| IV | 1395 (0.5) | 3 (0.1) | 1392 (0.5) | 18 (0.2) | 3 (0.1) | 15 (0.2) | ||
| Unknown | 11900 (4.4) | 38 (1.4) | 11862 (4.4) | 133 (1.2) | 38 (1.4) | 95 (1.2) | ||
| T stage | <0.001 | 1.000 | ||||||
| T1 | 221382 (81.7) | 2407 (87.6) | 218975 (81.7) | 9626 (87.6) | 2407 (87.6) | 7219 (87.6) | ||
| T2 | 49460 (18.3) | 342 (12.4) | 49118 (18.3) | 1366 (12.4) | 342 (12.4) | 1024 (12.4) | ||
| ER | <0.001 | 0.984 | ||||||
| Positive | 224278 (82.8) | 2587 (94.1) | 221691 (82.7) | 10350 (94.2) | 2587 (94.1) | 7763 (94.2) | ||
| Negative | 38092 (14.1) | 138 (5.0) | 37954 (14.2) | 545 (5.0) | 138 (5.0) | 407 (4.9) | ||
| Unknown | 8472 (3.1) | 24 (0.9) | 8448 (3.2) | 97 (0.9) | 24 (0.9) | 73 (0.9) | ||
| PR | <0.001 | 0.843 | ||||||
| Positive | 196087 (72.4) | 2373 (86.3) | 193714 (72.3) | 9497 (86.4) | 2373 (86.3) | 7124 (86.4) | ||
| Negative | 63872 (23.6) | 349 (12.7) | 63523 (23.7) | 1397 (12.7) | 349 (12.7) | 1048 (12.7) | ||
| Unknown | 10883 (4.0) | 27 (1.0) | 10856 (4.0) | 98 (0.9) | 27 (1.0) | 71 (0.9) | ||
| HER2 | <0.001 | 0.794 | ||||||
| Positive | 14470 (5.3) | 111 (4.0) | 14359 (5.4) | 416 (3.8) | 111 (4.0) | 305 (3.7) | ||
| Negative | 123784 (45.7) | 2347 (85.4) | 121437 (45.3) | 9420 (85.7) | 2347 (85.4) | 7073 (85.8) | ||
| Unknown | 5571 (2.1) | 66 (2.4) | 5505 (2.1) | 248 (2.3) | 66 (2.4) | 182 (2.2) | ||
| Unavailable | 127017 (46.9) | 225 (8.2) | 126792 (47.3) | 908 (8.3) | 225 (8.2) | 683 (8.3) | ||
| Molecular Subtype | <0.001 | 0.945 | ||||||
| HR + /HER2- | 111265 (41.1) | 2275 (82.8) | 108990 (40.7) | 9138 (83.1) | 2275 (82.8) | 6863 (83.3) | ||
| HR + /HER2 + | 10933 (4.0) | 96 (3.5) | 10837 (4.0) | 358 (3.3) | 96 (3.5) | 262 (3.2) | ||
| HER2 enriched | 3515 (1.3) | 15 (0.5) | 3500 (1.3) | 58 (0.5) | 15 (0.5) | 43 (0.5) | ||
| TNBC | 12410 (4.6) | 71 (2.6) | 12339 (4.6) | 280 (2.5) | 71 (2.6) | 209 (2.5) | ||
| Unknown | 132719 (49.0) | 292 (10.6) | 132427 (49.4) | 1158 (10.5) | 292 (10.6) | 866 (10.5) | ||
| Chemotherapy | <0.001 | 0.794 | ||||||
| Chemotherapy | 72158 (26.6) | 280 (10.2) | 71878 (26.8) | 1136 (10.3) | 280 (10.2) | 856 (10.4) | ||
| Chemotherapy-naïve | 198684 (73.4) | 2469 (89.8) | 196215 (73.2) | 9856 (89.7) | 2469 (89.8) | 7387 (89.6) | ||
| Total | 270842 | 2749 | 268093 | 10992 | 2749 | 8243 | ||
DSW, divorced/separated/widowed; EBRT, external beam radiotherapy; ER, estrogen receptor; HER2, human epidermal growth receptor 2; HR, hormone receptor; IORT, intraoperative radiotherapy; PR, progesterone receptor; TNBC, triple-negative breast cancer.