Research Article
The Volume-Outcome Relationship in Retroperitoneal Soft Tissue Sarcoma: Evidence of Improved Short- and Long-Term Outcomes at High-Volume Institutions
Table 2
Patient characteristics: all surgical cases.
| | | High volume (N = 401) | Medium volume (N = 235) | Low volume (N = 3167) | Total (N = 3803) | value |
| | Age at diagnosis | | 0.0045 | | Mean (SD) | 59.6 (13.7) | 58.7 (14.5) | 61.2 (13.9) | 60.9 (14.0) | | | Median | 60.0 | 60.0 | 62.0 | 62.0 | | | Q1, Q3 | 51.0, 69.0 | 50.0, 69.0 | 52.0, 71.0 | 52.0, 71.0 | | | Range | (20.0–90.0) | (19.0–87.0) | (18.0–90.0) | (18.0–90.0) |
| | Sex | | 0.0002 | | Male | 216 (53.9%) | 130 (55.3%) | 1438 (45.4%) | 1784 (46.9%) | | | Female | 185 (46.1%) | 105 (44.7%) | 1729 (54.6%) | 2019 (53.1%) |
| | Race | | 0.0010 | | Black | 21 (5.2%) | 15 (6.4%) | 350 (11.1%) | 386 (10.1%) | | | Other | 22 (5.5%) | 18 (7.7%) | 184 (5.8%) | 224 (5.9%) | | White | 358 (89.3%) | 202 (86.0%) | 2633 (83.1%) | 3193 (84.0%) |
| | Charlson–Deyo score | | 0.0061 | | 0 | 336 (83.8%) | 195 (83.0%) | 2444 (77.2%) | 2975 (78.2%) | | | 1 | 55 (13.7%) | 34 (14.5%) | 565 (17.8%) | 654 (17.2%) | | 2 | 10 (2.5%) | 6 (2.6%) | 158 (5.0%) | 174 (4.6%) |
| | Year of diagnosis | | 0.20 | | 2004 | 30 (7.5%) | 12 (5.1%) | 253 (8.0%) | 295 (7.8%) | | | 2005 | 31 (7.7%) | 19 (8.1%) | 259 (8.2%) | 309 (8.1%) | | 2006 | 40 (10.0%) | 18 (7.7%) | 271 (8.6%) | 329 (8.7%) | | 2007 | 43 (10.7%) | 18 (7.7%) | 310 (9.8%) | 371 (9.8%) | | 2008 | 51 (12.7%) | 22 (9.4%) | 306 (9.7%) | 379 (10.0%) | | 2009 | 44 (11.0%) | 22 (9.4%) | 314 (9.9%) | 380 (10.0%) | | 2010 | 36 (9.0%) | 22 (9.4%) | 350 (11.1%) | 408 (10.7%) | | 2011 | 38 (9.5%) | 42 (17.9%) | 389 (12.3%) | 469 (12.3%) | | 2012 | 44 (11.0%) | 36 (15.3%) | 359 (11.3%) | 439 (11.5%) | | 2013 | 44 (11.0%) | 24 (10.2%) | 356 (11.2%) | 424 (11.1%) |
| | Facility type | | <0.0001 | | Missing | 31 | 23 | 230 | 284 | | | Community cancer program | 0 (0.0%) | 0 (0.0%) | 121 (4.1%) | 121 (3.4%) | | Comprehensive community cancer program | 0 (0.0%) | 0 (0.0%) | 913 (31.1%) | 913 (25.9%) | | Academic/research program | 370 (100.0%) | 212 (100.0%) | 1579 (53.8%) | 2161 (61.4%) | | Integrated network cancer program | 0 (0.0%) | 0 (0.0%) | 324 (11.0%) | 324 (9.2%) |
| | Primary payor | | <0.0001 | | Not insured | 2 (0.5%) | 9 (3.8%) | 116 (3.7%) | 127 (3.3%) | | | Private insurance | 175 (43.6%) | 109 (46.4%) | 1482 (46.8%) | 1766 (46.4%) | | Medicaid | 6 (1.5%) | 18 (7.7%) | 189 (6.0%) | 213 (5.6%) | | Medicare | 102 (25.4%) | 96 (40.9%) | 1300 (41.0%) | 1498 (39.4%) | | Other government | 3 (0.7%) | 1 (0.4%) | 43 (1.4%) | 47 (1.2%) | | Insurance status unknown | 113 (28.2%) | 2 (0.9%) | 37 (1.2%) | 152 (4.0%) |
| | Median income quartiles | | 0.0002 | | Missing | 24 | 11 | 119 | 154 | | | <$30,000 | 25 (6.6%) | 14 (6.3%) | 387 (12.7%) | 426 (11.7%) | | $30,000–$35,999 | 61 (16.2%) | 49 (21.9%) | 521 (17.1%) | 631 (17.3%) | | $36,000–$45,999 | 93 (24.7%) | 61 (27.2%) | 807 (26.5%) | 961 (26.3%) | | $46,000+ | 198 (52.5%) | 100 (44.6%) | 1333 (43.7%) | 1631 (44.7%) |
| | No high school degree quartiles (%) | | 0.0001 | | Missing | 24 | 11 | 119 | 154 | | | ≥29% | 43 (11.4%) | 20 (8.9%) | 473 (15.5%) | 536 (14.7%) | | 20–28.9% | 62 (16.4%) | 55 (24.6%) | 694 (22.8%) | 811 (22.2%) | | 14–19.9% | 85 (22.5%) | 61 (27.2%) | 701 (23.0%) | 847 (23.2%) | | <14% | 187 (49.6%) | 88 (39.3%) | 1180 (38.7%) | 1455 (39.9%) |
| | Distance to treating center (miles) | | <0.0001 | | Mean (SD) | 259.0 (433.2) | 85.3 (149.5) | 42.5 (145.9) | 68.0 (208.0) | | | Median | 80.4 | 49.5 | 13.7 | 17.2 | | | Q1, Q3 | 22.9, 306.5 | 22.3, 100.3 | 5.4, 38.3 | 6.2, 50.8 | | | Range | (1.0–4040.1) | (1.0–1495.6) | (1.0–4710.1) | (1.0–4710.1) | |
| | Histologic subtype | | <0.0001 | | Dedifferentiated liposarcoma | 125 (31.2%) | 69 (29.4%) | 585 (18.5%) | 779 (20.5%) | | | Fibrosarcoma | 6 (1.5%) | 4 (1.7%) | 45 (1.4%) | 55 (1.4%) | | Leiomyosarcoma | 64 (16.0%) | 38 (16.2%) | 715 (22.6%) | 817 (21.5%) | | Liposarcoma | 143 (35.7%) | 64 (27.2%) | 1078 (34.0%) | 1285 (33.8%) | | MFH | 2 (0.5%) | 4 (1.7%) | 70 (2.2%) | 76 (2.0%) | | MPNST | 3 (0.7%) | 2 (0.9%) | 25 (0.8%) | 30 (0.8%) | | Rare/NOS | 58 (14.5%) | 54 (23.0%) | 649 (20.5%) | 761 (20.0%) |
| | Grade | | <0.0001 | | Missing | 62 | 53 | 617 | 732 | | | Well differentiated | 133 (39.2%) | 53 (29.1%) | 919 (36.0%) | 1105 (36.0%) | | Mod differentiated | 15 (4.4%) | 19 (10.4%) | 426 (16.7%) | 460 (15.0%) | | Poorly differentiated | 57 (16.8%) | 53 (29.1%) | 774 (30.4%) | 884 (28.8%) | | Undifferentiated | 134 (39.5%) | 57 (31.3%) | 431 (16.9%) | 622 (20.3%) |
| | Tumor size | | 0.11 | | Missing | 29 | 6 | 206 | 241 | | | 5–10 cm | 56 (15.1%) | 55 (24.0%) | 556 (18.8%) | 667 (18.7%) | | <5 cm | 29 (7.8%) | 17 (7.4%) | 236 (8.0%) | 282 (7.9%) | | >10 cm | 287 (77.2%) | 157 (68.6%) | 2169 (73.3%) | 2613 (73.4%) |
| | AJCC stage group | | 0.016 | | Stage I | 128 (31.9%) | 63 (26.8%) | 989 (31.2%) | 1180 (31.0%) | | | Stage II | 38 (9.5%) | 29 (12.3%) | 409 (12.9%) | 476 (12.5%) | | Stage III | 158 (39.4%) | 96 (40.9%) | 1044 (33.0%) | 1298 (34.1%) | | AJCC staging not applicable | 17 (4.2%) | 18 (7.7%) | 196 (6.2%) | 231 (6.1%) | | AJCC stage group unknown | 60 (15.0%) | 29 (12.3%) | 529 (16.7%) | 618 (16.3%) |
| | Margins | | 0.0001 | | Missing | 153 | 43 | 810 | 1006 | | | Grossly positive (R2) | 6 (2.4%) | 6 (3.1%) | 128 (5.4%) | 140 (5.0%) | | Microscopically positive (R1) | 40 (16.1%) | 61 (31.8%) | 621 (26.3%) | 722 (25.8%) | | Negative (R0) | 202 (81.5%) | 125 (65.1%) | 1608 (68.2%) | 1935 (69.2%) |
| | 30-day mortality | | 0.027 | | Patient alive or died more than 30 days after surgery performed | 399 (99.5%) | 232 (98.7%) | 3090 (97.6%) | 3721 (97.8%) | | | Patient died 30 or fewer days after surgery performed | 2 (0.5%) | 3 (1.3%) | 77 (2.4%) | 82 (2.2%) |
| | 90-day mortality | | 0.0012 | | Patient alive or died more than 90 days after surgery performed | 396 (98.8%) | 220 (93.6%) | 3000 (94.7%) | 3616 (95.1%) | | | Patient died 90 or fewer days after surgery performed | 5 (1.2%) | 15 (6.4%) | 167 (5.3%) | 187 (4.9%) |
| | Hospital volume | | <0.0001 | | Mean (SD) | 143.5 (38.4) | 60.9 (12.1) | 12.8 (11.2) | 29.5 (44.0) | | | Median | 108.0 | 53.0 | 8.0 | 11.0 | | | Q1, Q3 | 108.0, 185.0 | 53.0, 78.0 | 4.0, 18.0 | 5.0, 32.0 | | | Range | (108.0–185.0) | (51.0–78.0) | (1.0–45.0) | (1.0–185.0) | |
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