Table 1. Participant Characteristics.
| Baseline Characteristic | Patient Group | Control Group | Difference (95% CI) |
|---|---|---|---|
| No. (%) | 80 | 40 | |
| Age | |||
| Median (range) | 59 (41-76) | 54.5 (41-75) | |
| Mean (SD) | 58.3 (7.6) | 54.6 (8.4) | 3.7 (0.6 to 6.8) |
| Distribution (%) | |||
| <50 | 11 (14) | 11 (28) | |
| 50-59 | 34 (43) | 16 (40) | |
| 60-69 | 30 (38) | 12 (30) | |
| ≥70 | 5 (6) | 1 (3) | |
| Sex | |||
| Male, No. (%) | 68 (85) | 35 (88) | −2.5 (−15.3 to 14.0) |
| Education (coded no.) | −30.0 (−47.5 to −9.8)a | ||
| <High school | 17 (21) | 3 (8) | |
| High school with or without some college | 39 (49) | 13 (33) | |
| University degree | 15 (19) | 17 (43) | |
| Postgraduate degree | 9 (11) | 7 (18) | |
| ECOG performance status | |||
| 0 | 44 (55) | NA | NA |
| 1 | 32 (40) | ||
| 2 | 1 (1) | ||
| Missing | 3 (4) | ||
| Cigarette history (pack-years) | |||
| Median (range) | 17.5 (0-80) | 0 (0-56) | 14.5 (9.0 to 20.0) |
| Smoking status | |||
| Never smoker | 29 (36) | 24 (60) | 26.3 (6.2 to 42.5)b |
| ≤10 Pack-years | 10 (13) | 6 (15) | |
| >10 Pack-years | 41 (51) | 10 (25) | |
| Alcohol units per week | |||
| Mean (SD) | 16.2 (19) | 6.9 (5) | 16.3 (−3.4 to 32.7)c |
| Median (range) | 9 (0-140) | 9 (0-20) | |
| ≤10 | 47 (59) | 30 (75) | |
| >10 | 33 (41) | 10 (25) | |
| Comorbidities (heart disease, renal disease, hypertension, diabetes), No. | |||
| 0 | 49 (61) | 36 (90) | 28.8 (10.8 to 42.2)d |
| 1 | 16 (20) | 4 (10) | |
| ≥2 | 15 (19) | 0 (0) | |
| Remote concussion, No. (%) | 15 (19) | 8 (20) | −1.3 (−19.1 to 13.6) |
| Disease and treatment | |||
| Site | NA | NA | |
| Hypopharynx | 5 (6) | ||
| Oropharynx | 61 (76) | ||
| Laryngeal | 7 (9) | ||
| Nasal cavity | 2 (3) | ||
| Unknown primary | 5 (6) | ||
| HPV status | NA | NA | |
| Positive | 46 (58) | ||
| Negative | 11 (14) | ||
| Unknown | 23 (29) | ||
| Stage | NA | NA | |
| II | 3 (4) | ||
| III | 5 (6) | ||
| IVa | 70 (87) | ||
| IVb | 2 (3) | ||
| Max radiation dose to target | NA | NA | |
| 70 Gy in 35 fractions | 71 (89) | ||
| Other | 9 (11) | ||
| Max radiation dose to brain | |||
| Median highest drug concentration, Gy (range) | 56 (0.6-77.3) | ||
| Systemic treatment | NA | NA | |
| Cisplatin | 49 (61) | ||
| Carboplatin with or without fluorouracil | 2 (3) | ||
| Panitumumab | 18 (22) | ||
| None | 11 (14) |
Abbreviations: ECOG, Eastern Cooperative Oncology Group; NA, not applicable.
a
At least university education versus less than university.
b
>10 Pack-years of smoking versus ≤10 pack-years of smoking.
c
>10 Units of alcohol per week versus ≤10 units of alcohol per week.
d
≥1 Comorbidity versus 0 comorbidities.