Table 1. Patient Demographic, Disease, and Treatment Characteristics.
| No. (%) | Total population | Received CRT | Received RT | P valuea |
|---|---|---|---|---|
| Sex | ||||
| Men | 24 189 (72.1) | 11 165 (75.6) | 13 024 (69.5) | <.001 |
| Women | 9338 (27.9) | 3610 (24.4) | 5728 (30.5) | |
| Age, y | ||||
| >70 | 5491 (16.4) | 1517 (10.3) | 3974 (21.2) | <.001 |
| ≤70 | 28 036 (83.6) | 13 258 (89.7) | 14 778 (78.8) | |
| Year of diagnosis | ||||
| 2004-2008 | 9697 (28.9) | 4461 (30.2) | 5236 (27.9) | <.001 |
| 2009-2012 | 10 750 (32.1) | 5126 (34.7) | 5624 (30.0) | |
| 2013-2016 | 13 080 (39.0) | 5188 (35.1) | 7892 (42.1) | |
| Race | ||||
| White | 29 261 (87.3) | 12 940 (87.6) | 16 321 (87) | .10 |
| Black | 2801 (8.4) | 1229 (8.3) | 1572 (8.4) | |
| Other or unknown | 1465 (4.4) | 606 (4.1) | 859 (4.6) | |
| Academic center | 18 842 (56.2) | 7857 (53.2) | 10 985 (58.6) | <.001 |
| Charlson/Deyo Score | ||||
| 0-1 | 31 752 (94.7) | 14 105 (95.5) | 17 647 (94.1) | <.001 |
| 2-3 | 1775 (5.3) | 670 (4.5) | 1105 (5.9) | |
| Status at last contact | ||||
| Alive | 21 615 (64.5) | 9423 (63.8) | 12 192 (65.0) | .06 |
| Dead | 11 912 (35.5) | 5352 (36.2) | 6560 (35.0) | |
| Primary site | ||||
| Oral cavity | 15 814 (47.2) | 5967 (40.4) | 9847 (52.5) | <.001 |
| Buccal mucosa | 1082 (3.2) | 369 (2.5) | 713 (3.8) | |
| Alveolar ridge | 2296 (6.8) | 714 (4.8) | 1582 (8.4) | |
| Retromolar trigone | 1118 (3.3) | 439 (3.0) | 679 (3.6) | |
| Tongue | 7207 (21.5) | 2822 (19.1) | 4385 (23.4) | |
| Oropharynx | 11 162 (33.3) | 6086 (41.2) | 5076 (27.1) | |
| Tonsils | 7347 (21.9) | 4209 (28.5) | 3138 (16.7) | |
| Base of tongue | 2997 (8.9) | 1488 (10.1) | 1509 (8.0) | |
| Hypopharynx | 920 (2.7) | 500 (3.4) | 420 (2.2) | |
| Larynx | 5631 (16.8) | 2222 (15.0) | 3409 (18.2) | |
| Tumor stage | ||||
| T1 | 8544 (25.5) | 3859 (26.1) | 4685 (25.0) | .02 |
| T2 | 10 249 (30.6) | 4408 (29.8) | 5841 (31.1) | |
| T3 | 4711 (14.1) | 2104 (14.2) | 2607 (13.9) | |
| T4 | 10 023 (29.9) | 4404 (29.8) | 5619 (30.0) | |
| Nodal stage | ||||
| N0 | 11 038 (32.9) | 2596 (17.6) | 8442 (45.0) | <.001 |
| N1 | 6674 (19.9) | 2578 (17.4) | 4096 (21.8) | |
| N2 | 15 290 (45.6) | 9201 (62.3) | 6089 (32.5) | |
| N3 | 525 (1.6) | 400 (2.7) | 125 (0.7) | |
| Measured tumor size, median (IQR), mm | 3.3 (2.0-3.7) | 3.3 (2.0-4.0) | 3.2 (2.0-3.5) | <.001 |
| Tumor thickness, median (IQR), mmb | 62.7 (10.0-90.0) | 6.46 (11.0-90.0) | 6.18 (10.0-90.0) | .01 |
| Differentiation | ||||
| Well differentiated | 3309 (9.9) | 1086 (7.4) | 2223 (11.9) | <.001 |
| Moderately differentiated | 17 645 (52.6) | 7461 (50.5) | 10 184 (54.3) | |
| Poorly differentiated or anaplastic | 10 055 (30.0) | 4929 (33.4) | 5126 (27.3) | |
| LVI | 4654 (13.9) | 2449 (16.6) | 2205 (11.8) | <.001 |
| Lymph nodes positive | ||||
| 0 | 9143 (27.3) | 2074 (14.0) | 7069 (37.7) | <.001 |
| 1 | 7916 (23.6) | 3351 (22.7) | 4565 (24.3) | |
| 2-4 | 13 184 (39.3) | 6870 (46.5) | 6314 (33.7) | |
| 5-9 | 2499 (7.5) | 1849 (12.5) | 650 (3.5) | |
| ≥10 | 785 (2.3) | 631 (4.3) | 154 (0.8) | |
| Lymph node levels involved | ||||
| I | 6404 (19.1) | 3666 (24.8) | 2738 (14.6) | <.001 |
| II | 14 212 (42.4) | 8240 (55.8) | 5972 (31.8) | <.001 |
| III | 7936 (23.7) | 4902 (33.2) | 3034 (16.2) | <.001 |
| IV | 3047 (9.1) | 2086 (14.1) | 961 (5.1) | <.001 |
| V | 1153 (3.4) | 853 (5.8) | 300 (1.6) | <.001 |
| Retropharyngeal | 265 (0.8) | 182 (1.2) | 83 (0.4) | <.001 |
| Parapharyngeal | 275 (0.8) | 165 (1.1) | 110 (0.6) | <.001 |
| HPV positivityc | ||||
| Oropharynx | 4038 (77.8) | 1994 (77.3) | 2044 (78.3) | .77 |
| Nonoropharynx | 669 (16.0) | 297 (16.9) | 372 (15.3) | .13 |
| HPV positivity, imputedd | ||||
| Oropharynx, % | 73.3 | 74.2 | 72.4 | NA |
| Nonoropharynx, % | 16.7 | 17.8 | 16.1 | NA |
| Multiagent chemotherapy | 2945 (8.8) | 2945 (19.9) | 0 (0.0) | |
| Time from surgery to completion of RT | ||||
| >100 d | 15 744 (47.0) | 7017 (47.5) | 8727 (46.5) | .004 |
| ≤100 d | 17 783 (53.0) | 7758 (52.5) | 10 025 (53.5) | |
| RT dose | ||||
| 50-59 Gy | 4734 (14.1) | 2535 (17.2) | 2199 (11.7) | <.001 |
| 60-69 Gy | 5848 (17.4) | 2230 (15.1) | 3618 (19.3) | |
| ≥70 Gy | 22 948 (68.4) | 9501 (64.3) | 13 447 (71.7) | |
| Adequate lymph node dissection, ie, ≥18+ nodes examined | 4731 (14.1) | 3044 (20.6) | 1687 (9.0) | <.001 |
Abbreviation: CRT, chemoradiotherapy; HPV, human papillomavirus; IQR, interquartile range; LVI, lymphovascular invasion; NA, not applicable; RT, radiotherapy.
a
For categorical values, the P value for a χ2 test comparing the CRT and RT groups is provided; for numerical values, the P value for an unpaired 2-sided t test is provided.
b
Values listed for the oral cavity subgroup prior to imputation, given that tumor thickness is not available and/or not applicable for other primary tumor sites.
c
Percentage listed indicates percentage positive out of all patients from whom HPV status is reported.
d
The regressor used to impute HPV status assigns a likelihood from 0 to 1 of HPV positivity for each case. Mean imputed HPV status is listed as a percentage to allow comparison with true HPV rates.