Table 2.
Colorectal-Cancer Incidence and Mortality.*
| Variable | Flexible-Sig moidoscopy Group (N = 77,445) | Usual-Care Group (N = 77,455) | Relative Risk (95% CI) | P Value | ||
|---|---|---|---|---|---|---|
| no. of participants | rate per 10,000 person-yr (95% CI) | no. of participants | rate per 10,000 person-yr (95% CI) | |||
| Incidence | ||||||
| All colorectal cancers | 1012 | 11.9 (11.2–12.7) | 1287 | 15.2 (14.4–16.0) | 0.79 (0.72–0.85) | <0.001 |
| Location of cancer† | ||||||
| Distal | 479 | 5.6 (5.1–6.2) | 669 | 7.9 (7.3–8.5) | 0.71 (0.64–0.80) | <0.001 |
| Proximal | 512 | 6.0 (5.5–6.6) | 595 | 7.0 (6.5–7.6) | 0.86 (0.76–0.97) | 0.01 |
| Sex | ||||||
| Male | 567 | 13.6 (12.4–14.7) | 768 | 18.5 (17.2–19.9) | 0.73 (0.66–0.82) | <0.001 |
| Female | 445 | 10.3 (9.4–11.3) | 519 | 12.0 (11.0–13.0) | 0.86 (0.76–0.98) | 0.02 |
| Age at randomization | ||||||
| 55–64 yr | 518 | 9.4 (8.6–10.2) | 662 | 12.1 (11.2–13.0) | 0.78 (0.69–0.87) | <0.001 |
| 65–74 yr | 494 | 16.6 (15.1–18.1) | 625 | 20.9 (19.3–22.5) | 0.79 (0.71–0.89) | <0.001 |
| Mortality | ||||||
| All colorectal-cancer deaths | 252 | 2.9 (2.5–3.2) | 341 | 3.9 (3.5–4.3) | 0.74 (0.63–0.87) | <0.001 |
| Location of cancer† | ||||||
| Distal | 87 | 1.0 (0.8–1.2) | 175 | 2.0 (1.7–2.3) | 0.50 (0.38–0.64) | <0.001 |
| Proximal | 143 | 1.6 (1.4–1.9) | 147 | 1.7 (1.4–2.0) | 0.97 (0.77–1.22) | 0.81 |
| Sex | ||||||
| Male | 139 | 3.2 (2.7–3.8) | 211 | 4.9 (4.3–5.6) | 0.66 (0.53–0.81) | <0.001 |
| Female | 113 | 2.6 (2.1–3.0) | 130 | 2.9 (2.4–3.4) | 0.87 (0.68–1.12) | 0.28 |
| Age at randomization | ||||||
| 55–64 yr | 133 | 2.4 (2.0–2.8) | 157 | 2.8 (2.3–3.2) | 0.84 (0.67–1.06) | 0.16 |
| 65–74 yr | 119 | 3.9 (3.2–4.6) | 184 | 6.0 (5.1–6.9) | 0.65 (0.52–0.82) | <0.001 |
*
The median follow-up time for incidence was 11.9 years (interquartile range, 10.2 to 13.0) and for mortality was 12.1 years (interquartile range, 10.4 to 13.0).
†
Distal location was defined as the rectum through the splenic flexure, and proximal as the transverse colon through the cecum. For incidence, the location was unknown for 21 cases in the flexible-sigmoidoscopy group and 23 cases in the usual-care group. For mortality, the location was unknown for 22 deaths in the flexible-sigmoidoscopy group and 19 deaths in the usual-care group.