| Author | Groves | Saurin | Bulow |
| Year of publication | 2002 | 2004 | 2004 |
| Subjects | 99 | 35 | 368 |
| Mean age (years) | 42 | 37 | 25 |
| Sex (% male) | 55 | 57 | 49 |
| Mean follow-up (years) | 10 | 4 | 7.6 |
| Spigelman stage IV | |||
| at initial examination | 9.6% | 14% | 7% |
| at last follow-up | 14% | 35% | 15% |
| Duodenal cancer during follow-up | 6* | 0 | 4† |
*Spigelman stage at previous endoscopy: II, III, IV, IV, IV, IV.
†Spigelman stage at previous endoscopy: II, III, IV, IV.