Table 4.
Colorectal-Cancer Incidence and Mortality According to Location and Stage.
| Variable | Cancer Stage | Total | |||||
|---|---|---|---|---|---|---|---|
| I | II | III | IV | Carcinoid | Unknown | ||
| Flexible-sigmoidoscopy group | |||||||
| Cases of colorectal cancer — no. | 334 | 240 | 241 | 140 | 32 | 25 | 1012 |
| Deaths from colorectal cancer — no. (%) | 20 (6.0) | 26 (10.8) | 70 (29.0) | 113 (80.7) | 3 (9.4) | 20 (80.0) | 252 (24.9) |
| Cases of distal colorectal cancer — no. | 202 | 110 | 96 | 41 | 24 | 6 | 479 |
| Deaths from distal colorectal cancer — no. (%) | 11 (5.4) | 15 (13.6) | 28 (29.2) | 33 (80.5) | 0 | 0 | 87 (18.2) |
| Cases of proximal colorectal cancer — no. | 131 | 130 | 145 | 96 | 8 | 2 | 512 |
| Deaths from proximal colorectal cancer — no. (%) | 9 (6.9) | 11 (8.5) | 42 (29.0) | 78 (81.2) | 3 (37.5) | 0 | 143 (27.9) |
| Usual-care group | |||||||
| Cases of colorectal cancer — no. | 407 | 309 | 328 | 209 | 9 | 25 | 1287 |
| Deaths from colorectal cancer — no. (%) | 21 (5.2) | 33 (10.7) | 102 (31.1) | 163 (78.0) | 4 (44.4) | 18 (72.0) | 341 (26.5) |
| Cases of distal colorectal cancer — no. | 252 | 144 | 157 | 107 | 3 | 6 | 669 |
| Deaths from distal colorectal cancer — no. (%) | 14 (5.6) | 25 (17.4) | 50 (31.8) | 84 (78.5) | 1 (33.3) | 1 (16.7) | 175 (26.2) |
| Cases of proximal colorectal cancer — no. | 153 | 164 | 170 | 98 | 6 | 4 | 595 |
| Deaths from proximal colorectal cancer — no. (%) | 7 (4.6) | 8 (4.9) | 52 (30.6) | 77 (78.6) | 3 (50.0) | 0 | 147 (24.7) |
| Between-group differences* | |||||||
| Distal colorectal cancer | |||||||
| Cases — no. (% reduction in incidence) | 50 (19.8) | 34 (23.6) | 61 (38.9) | 66 (61.7) | -21 (-700.0) | 0 | 190 |
| Deaths — no. (% reduction in mortality) | 3 (21.4) | 10 (40.0) | 22 (44.0) | 51 (60.7) | 1 (100.0) | 1 (100.0) | 88 |
| Proximal colorectal cancer | |||||||
| Cases — no. (% reduction in incidence) | 22 (14.4) | 34 (20.7) | 25 (14.7) | 2 (2.0) | −2 (−33.3) | 2 (50.0) | 83 |
| Deaths — no. (% reduction in mortality) | −2 (−8.6) | −3 (−37.5) | 10 (19.2) | −1 (−1.3) | 0 | 0 | 4 |
*
Differences in cases and deaths were calculated as the number in the usual-care group minus the number in the flexible-sigmoidoscopy group. The percentage difference was calculated as 100 – [(flexible-sigmoidoscopy rate ÷ usual-care rate) × 100]. The flexible-sigmoidoscopy rate was defined as cases in the flexible-sigmoidoscopy group divided by the flexible-sigmoidoscopy population, and the usual-care rate as cases in the usual-care group divided by the usual-care population.