Characteristics of patients with hyperplastic polyposis syndrome (HPS) from multiple centres in The Netherlands, divided per centre
| All centres (n=77) | Centre 1 (n=43) | Centre 2 (n=8) | Centre 3 (n=7) | Centre 4 (n=6) | Centre 5 (n=5) | Centre 6 (n=5) | Centre 7 (n=3) | |
| Median age at diagnosis (range) | 56 (40–74) | 55 (40–74) | 51 (42–69) | 56 (46–65) | 58 (56–67) | 51 (43–72) | 52 (45–61) | 57 (48–69) |
| Mean follow-up time in years (range) | 5.6 (0.5–26.6) | 4.4 (1.3–9.3) | 10.6 (2.9–26.4) | 6.4 (1.1–12.3) | 2.6 (1.2–5.1) | 4.3 (3.0–5.7) | 2.2 (1.5–4.1) | 4.4 (1.3–9.3) |
| Mean follow-up time after HPS diagnosis in years (range) | 4.0 (0.4–21.0) | 3.2 (1.3–6.1) | 8.1 (1.1–20.8) | 5.8 (1.1–11.7) | 2.1 (1.2–4.4) | 3.3 (1.9–4.7) | 2.2 (1.5–4.1) | 3.2 (1.3–6.1) |
| Median interval endoscopies in months (range) | 11 (1–96) | 9 (1–96) | 23 (5–26) | 7 (3–63) | 6 (1–17) | 8 (1–24) | 11 (3–53) | 13 (10–25) |
| Median number of HPs in patients (range) | 15 (2–53) | 14 (2–53) | 29 (11–73) | 25 (6–45) | 10 (6–27) | 12 (2–22) | 21 (9–41) | 16 (5–18) |
| Median number of proximal HPs in patients (range) | 8 (1–45) | 7 (1–30) | 29 (5–45) | 10 (2–21) | 7 (2–12) | 6 (2–12) | 10 (4–30) | 5 (5–13) |
| Number of patients with an HP > 10 mm | 47 (61%) | 25 (58%) | 5 (63%) | 5 (71%) | 3 (50%) | 4 (80%) | 4 (80%) | 1 (33%) |
| Patients with >1 SA | 40 (52%) | 32 (74%) | 1 (13%) | 2 (29%) | 1 (17%) | 3 (60%) | 0 | 1 (33%) |
| Median number of SAs in patients (range) | 1 (0–24) | 5 (0–24) | 0(0–6) | 0(0–8) | 0(0–1) | 1 (0–20) | 0 | 0 (0–1) |
| Patients with >1 adenoma | 53 (69%) | 31 (72%) | 6 (75%) | 6 (86%) | 3 (50%) | 4 (80%) | 3 (60%) | 0 (0–1) |
| Median number of adenomas in patients (range) | 2 (0–26) | 2 (0–26) | 2 (0–16) | 6 (0–14) | 1 (0–9) | 2 (0–3) | 1 (0–5) | 0 (0–7) |
| Patients with CRC | 27 (35%) | 15 (35%) | 6 (75%) | 3 (43%) | 1 (17%) | 0 | 0 | 2 (67%) |
| At initial endoscopy | 22 (28.5%) | 11 (73%) | 6 (100%) | 2 (67%) | 1 (100%) | 0 | 0 | 2 (100%) |
| Interval CRC | 5 (6.5%) | 4 (27%) | 0 | 1 (33%) | 0 | 0 | 0 | 0 |
| Total polyps | 1984 | 1124 | 295 | 216 | 87 | 93 | 117 | 50 |
| Number of HPs | 1407 (72%) | 705 (63%) | 258 (87%) | 161 (74%) | 74 (85%) | 61 (67%) | 109 (93%) | 39 (78%) |
| Number of SAs | 302 (15%) | 259 (23%) | 6 (2%) | 9 (4%) | 1 (1%) | 23 (25%) | 0 | 4 (8%) |
| Number of MPs | 2 (0.1%) | 2 (0.2%) | 0 | 0 | 0 | 0 | 0 | 0 |
| Number of adenomas | 273 (14%) | 160 (14%) | 31 (11%) | 46 (22%) | 12 (14%) | 9 (8%) | 8 (7%) | 7 (14%) |
CRC, colorectal cancer; HPs, hyperplastic polyps; SAs, serrated adenomas.