Table 2.
Risk of colorectal cancer due to UV exposures by HRT status1
| Combined population | Never/Past HRT | Current HRT | |||||||
|---|---|---|---|---|---|---|---|---|---|
| No. cases | No. controls | OR (95% CI) | No. cases | No. controls | OR (95% CI) | No. cases | No. controls | OR (95% CI) | |
| Personal UV exposure | |||||||||
| ≤3.5 h/wk | 19 | 2865 | 1.0 | 12 | 1453 | 1.0 | 6 | 1343 | 1.0 |
| >3.5–7.0 | 11 | 2831 | 0.67 (0.32–1.41) | 6 | 1287 | 0.66 (0.25–1.76) | 5 | 1479 | 0.87 (0.27–2.89) |
| >7.0–14.0 | 28 | 5679 | 0.81 (0.45–1.46) | 13 | 2646 | 0.67 (0.30–1.47) | 15 | 2893 | 1.25 (0.48–3.25) |
| >14.0 | 37 | 8392 | 0.77 (0.44–1.35) | 17 | 3884 | 0.64 (0.30–1.34) | 19 | 4293 | 1.13 (0.45–2.85) |
| P-trend | 0.52 | 0.29 | 0.71 | ||||||
| P-Interaction | 0.34 | ||||||||
| Ambient exposure (TOMS Summer UV) (tertiles) | (kj/m2) | ||||||||
| 0–182.982 | 38 | 6535 | 1.0 | 24 | 3315 | 1.0 | 12 | 3063 | 1.0 |
| 182.982 -<211.400 | 36 | 6898 | 0.92 (0.58–1.46) | 19 | 3365 | 0.81 (0.44–1.49) | 17 | 3368 | 1.31 (0.62–2.75) |
| >211.400 | 23 | 6601 | 0.64 (0.38–1.07) | 7 | 2712 | 0.40 (0.17–0.93) | 16 | 3717 | 1.11 (0.52–2.35) |
| P-trend | 0.11 | 0.035 | 0.85 | ||||||
| P-Interaction | 0.07 | ||||||||
| Combined personal and ambient exposure2 | |||||||||
| Low | 24 | 2622 | 1.0 | 16 | 1375 | 1.0 | 7 | 1181 | 1.0 |
| Medium | 35 | 9471 | 0.44 (0.26–0.74) | 17 | 4563 | 0.36 (0.18–0.71) | 17 | 4683 | 0.64 (0.26–1.55) |
| High | 34 | 6795 | 0.63 (0.37– 1.06) | 14 | 2917 | 0.50 (0.24–1.03) | 20 | 3706 | 0.96 (0.40–2.28) |
| p-Trend | 0.24 | 0.09 | 0.70 | ||||||
| P-Interaction | 0.26 | ||||||||
1
Adusted for age, race, BMI, and HRT (in unstratified analysis; and personal and ambient exposures mutually adjusted for each other. Missing values are included as separate categories.
2
High= >7 h/week outdoors and ≥50 percentile ambient UV (TOMS summer); low= <=7 h/week outdoors and <50 percentile ambient UV; medium = all others.