Participant demographics
| Category (p value for difference*) | Asymptomatic context cohort | Symptomatic context cohort | Total (%) |
| Total N | 601 | 601 | 1202 (100) |
| Age (years) (p=0.987) | |||
| 18–29 | 140 | 146 | 286 (23.8) |
| 30–39 | 143 | 135 | 278 (23.1) |
| 40–49 | 106 | 111 | 217 (18.1) |
| 50–59 | 100 | 97 | 197 (16.4) |
| 60–69 | 86 | 88 | 174 (14.5) |
| ≥70 | 26 | 24 | 50 (4.2) |
| Sex† (p=0.414) | |||
| Female | 318 | 295 | 613 (51.0) |
| Male | 282 | 305 | 587 (48.8) |
| Other | 1 | 1 | 2 (0.2) |
| Simplified ethnicity (p=0.921) | |||
| Asian | 43 | 38 | 81 (6.7) |
| Black | 24 | 23 | 47 (3.9) |
| Mixed | 13 | 16 | 29 (2.4) |
| White | 515 | 516 | 1031 (85.8) |
| Other | 6 | 8 | 14 (1.2) |
| Self-reported socioeconomic status decile (p=0.200) | |||
| 1–3 (lowest) | 168 | 153 | 321 (26.7) |
| 4–5 | 195 | 212 | 407 (33.9) |
| 6–7 | 213 | 198 | 411 (34.2) |
| 8–10 (highest) | 25 | 38 | 63 (5.2) |
| Educational level (p=0.780) | |||
| Not completed A levels, further education or equivalent | 100 | 94 | 194 (16.1) |
| Competed A levels, further education or equivalent | 191 | 188 | 379 (31.5) |
| Completed a bachelor’s degree | 216 | 212 | 428 (35.6) |
| Completed a postgraduate degree | 94 | 107 | 201 (16.7) |
| Location (p=0.782) | |||
| England | 511 | 498 | 1009 (83.9) |
| Northern Ireland | 14 | 15 | 29 (2.4) |
| Scotland | 52 | 60 | 112 (9.3) |
| Wales | 24 | 28 | 52 (4.3) |
| Smoking status (p=0.432) | |||
| Never smoked | 358 | 351 | 709 (59.0) |
| Used to smoke | 178 | 195 | 373 (31.0) |
| Current smoker | 65 | 55 | 120 (10.0) |
| Weight (p=0.347) | |||
| Underweight | 31 | 21 | 52 (4.3) |
| About the right weight | 314 | 314 | 628 (52.3) |
| Overweight | 256 | 266 | 522 (43.4) |
| Personal history of cancer (p=0.016) | |||
| Yes | 35 | 18 | 53 (4.4) |
| No | 562 | 582 | 1144 (95.2) |
| Not reported | 4 | 1 | 5 (0.4) |
| Previously have completed cancer screening (p=0.646) | |||
| Yes | 281 | 265 | 546 (45.4) |
| No (chose not to) | 37 | 38 | 75 (6.2) |
| No (never been invited) | 280 | 295 | 575 (47.8) |
| Not reported | 3 | 3 | 6 (0.5) |
*p value for difference between asymptomatic and symptomatic context cohorts based on X2 tests.
†19 (1.6%) participants reported that their gender was not the same as the sex that they were assigned at birth. Of these, nine participants identified as non-binary.