Baseline characteristics
| Total cohort size; n | 434 |
| Age at diagnosis; median (IQR) | 60.8 (51.7–67.0) |
| Male gender; n (%) | 211 (48.6) |
| WHO subtype; n (%) | |
| Type 1 | 117 (27.0) |
| Type 3 | 179 (41.2) |
| Type 1+3 | 138 (31.8) |
| Smoking status; n (%) | |
| Current smoker | 126 (39.4) |
| Former smoker | 56 (17.5) |
| No smoker | 138 (43.1) |
| Missing | 114 |
| BMI; n (%) | |
| ≥30 kg/m2 | 41 (16.2) |
| <30 kg/m2 | 212 (83.8) |
| Missing | 181 |
| FDR with CRC; n (%) | |
| Yes | 149 (38.4) |
| No | 239 (61.6) |
| Missing | 46 |
| FDR with SPS; n (%) | |
| Yes | 25 (5.9) |
| No | 409 (94.1) |
| Clinical presentation; n (%) | |
| Symptoms | 308 (71.0) |
| Familial cancer risk | 69 (15.9) |
| Population screening | 57 (13.1) |
| Overview of detected polyps per patient | |
| No. of SPs; median (IQR) | 29 (17–50) |
| No. of SPs proximal to the rectosigmoid; median (IQR) | 14 (7–25) |
| No. of SPs ≥10 mm; median (IQR) | 3 (1–5) |
| Patients with at least 1 SP ≥10 mm; n (%) | 330 (76.0) |
| No. of SPs ≥10 mm proximal to the rectosigmoid; median (IQR) | 3 (0–5) |
| Patients with at least 1 SP ≥10 mm proximal to the rectosigmoid; n (%) | 310 (71.4) |
| No. of SPs containing dysplasia; median (range) | 0 (0–18) |
| Patients with at least 1 SP-containing dysplasia; n (%) | 114 (26.3) |
| No. of adenomas; median (IQR) | 2 (0–5) |
| Patients with at least 1 adenoma; n (%) | 324 (74.7) |
| No. of advanced adenomas; median (range) | 0 (0–6) |
| Patients with at least 1 advanced adenoma; n (%) | 153 (35.3) |
BMI, body mass index; CRC, colorectal cancer; FDR, first-degree relative; SPs, serrated polyps; SPS, serrated polyposis syndrome.