Table III.
GST genotype and smoking-related colorectal cancer risk
| Controls | Colorectal cancer | Colon cancer | Rectal cancer | ||||
| Cases | OR (95% CI) | Cases | OR (95% CI) | Cases | OR (95% CI) | ||
| With zero GST ‘null or low activity’ genotypea | |||||||
| Never smokers | 181 | 63 | 1.00 | 44 | 1.00 | 19 | 1.00 |
| Light smokers | 75 | 37 | 0.82 (0.43–1.55) | 15 | 0.35 (0.15–0.84) | 22 | 2.00 (0.81–4.90) |
| Heavy smokers | 7 | 8 | 1.34 (0.38–4.76) | 4 | 0.68 (0.14–3.22) | 4 | 3.23 (0.57–18.11) |
| P for trend | 0.916 | 0.087 | 0.085 | ||||
| With one GST ‘null or low activity’ genotypea | |||||||
| Never smokers | 350 | 126 | 1.00 | 81 | 1.00 | 45 | 1.00 |
| Light smokers | 120 | 69 | 1.09 (0.70–1.68) | 32 | 0.86 (0.50–1.49) | 37 | 1.37 (0.77–2.44) |
| Heavy smokers | 13 | 14 | 2.43 (1.01–5.86) | 6 | 2.05 (0.66–6.33) | 8 | 3.01 (1.05–8.62) |
| P for trend | 0.143 | 0.732 | 0.052 | ||||
| With two to three GST ‘null or low activity’ genotypesa | |||||||
| Never smokers | 314 | 84 | 1.00 | 50 | 1.00 | 34 | 1.00 |
| Light smokers | 97 | 61 | 1.69 (1.03–2.77) | 36 | 1.92 (1.04–3.54) | 25 | 1.39 (0.71–2.72) |
| Heavy smokers | 10 | 18 | 5.43 (2.22–13.23) | 7 | 4.25 (1.36–13.30) | 11 | 6.04 (2.14–17.04) |
| P for trend | 0.0002 | 0.005 | 0.003 | ||||
All ORs were adjusted for age, gender, dialect group, year of recruitment, level of education, body mass index, history of diabetes, family history of colorectal cancer, alcohol consumption, dietary intake of isothiocyanates and physical exercise.
a
Null or low activity genotypes were GSTM1 null, GSTT1 null and GSTP1 AB/BB genotype.