Table 3.
Output of following with endoscopy among high-risk population with history of polyps
| Year | Expected n | Observed n (%) | Adenoma n (%) | Non-adenomatous n (%) | Colorectal cancern (1/100000) |
| 1st group | |||||
| 1979 | 2803 | 2197 (78.38) | 178 (8.10) | 104 (4.73) | 6 (273.10) |
| 1981 | 2763 | 1592 (57.62) | 61 (3.83) | 27 (1.70) | 4 (251.26) |
| 1983 | 2719 | 2147 (78.96) | 108 (5.03) | 33 (1.54) | 2 (93.15) |
| 1987* | 2689 | 2408 (89.52) | 191 (7.93) | 96 (4.00) | 4 (166.11) |
| 1993* | 2388 | 1475 (61.77) | 121 (8.20) | 52 (3.53) | 4 (271.19) |
| 1998* | 2207 | 1020 (46.22) | 95 (9.31) | 17 (1.67) | 4 (392.16) |
| 2nd group | |||||
| 1982 | 1253 | 461 (36.79) | 17 (3.69) | 6 (1.30) | 0 (0.00) |
| 1984 | 1235 | 1056 (85.51) | 49 (4.64) | 26 (2.46) | 0 (0.00) |
| 1988* | 1183 | 931 (78.70) | 64 (6.87) | 20 (2.15) | 0 (0.00) |
| 1994* | 1097 | 479 (43.66) | 33 (6.68) | 17 (3.55) | 3 (626.30) |
| 1998* | 1040 | 486 (46.73) | 36 (7.41) | 17 (3.50) | 0 (0.00) |
| Total | 1425 | 2953 (6.68) | 417 (2.93) | 27 (189.45) |
*
Following with 60 cm flexible sigmoidoscopy since 1987