Colorectal cancer, diet and lifestyle factors: opportunities for prevention

A considerable amount of observational evidence from case-control and cohort studies demonstrates an association between various dietary and lifestyle factors and risk of colorectal cancer. This suggests the potential for colorectal cancer risk reduction by decreasing consumption of animal fats, red meat, alcohol and cigarettes, by increasing physical activity levels, and by increasing intake of fruits, vegetables and dietary fibre. Few intervention studies have been performed to corroborate this potential, although results of important trials will be available in the future. We argue, however, that the evidence is sufficient to support pilot implementation of lifestyle-modification programs in the context of targeted screening programs, and also the integration of prevention of colorectal cancer within a non-communicable disease strategy aimed at the general population. Evaluation of the costs and benefits of alternative strategies must be an integral part of program implementation, in order to advance the knowledge that we have of the impact of prevention strategies, so that resources are not wasted on ineffective interventions. Given the consistency of evidence relating lifestyle behaviours to colorectal cancer incidence and the negligible risk of undesirable consequences from promotion of a diet high in fruit, vegetables and fibre and low in red meat and animal fats, inaction can no longer be justified.Key words: colorectal cancer; diet; primary prevention