Interplay between dietary inducers of GST and the genotype in colon cancer

The purpose of this study is to determine if cruciferous vegetables and coffee, two dietary inducers of glutatione-S-transferases, interact with GSTM-1 genotype to alter risk of colon cancer. Data were available on 1579 incident cases of adenocarcinoma of the colon and 1898 population-based controls. Intake of cruciferous vegetables, specific types of cruciferous vegetable, and coffee were not associated with colon cancer; GSTM-1 genotype did not modify these associations. However, age at diagnosis and cigarette smoking appeared to be important effect modifiers of the associations between GSTM-1, cruciferous vegetables and colon cancer. Among GSTM-1 null individuals, <55 years at diagnosis, we observed an inverse association between colon cancer and high levels of cruciferous vegetable intake relative to people who did not eat cruciferous vegetables (ORs 0.23 95␌I 0.10-0.54); broccoli was the cruciferous vegetable associated with the strongest inverse association (OR 0.30 95␌I 0.13-0.70). Among younger individuals who were GSTM-1 present (relative to those with GSTM-1 null), we observed an inverse association with colon cancer regardless of level of cruciferous vegetable intake (OR 0.74 95␌I 0.30-1.79 for no intake; OR 0.44 95␌I 0.21-0.92 for <4 servings/week; and OR 0.44 95␌I 0.19-0.99 for 4 servings/week). These associations were further modified by cigarette smoking. People