The results show that all of the carcinogens, oncogenes, and tumor-associated viruses that we have studied profoundly affect the extent of 2- and 16 alpha-hydroxylation in a prorisk direction. All of the dietary and biological responses associated with increased cancer risk decrease 2-hydroxylation and increase 16 alpha-hydroxylation. Remarkably, although PAHs are reported to induce P450-1A1, we have found them to decrease 2-hydroxylation. Finally, using indole-3-carbinol to induce 2-hydroxylation results in the chemoprevention of mammary tumors in rodents and recurrences of laryngeal papillomas in humans. Also correlating with these studies in HPV is the decrease in the C-2/C-16 alpha metabolite ratio observed in women with CIN relative to control subjects. The greatest decrease was observed in women with the most severe form, CIN3 (Figure 23). These findings are under further investigation.