Energy balance and other modifiable host factors on colorectal cancer prognosis

Abstract

Epidemiologic and scientific research indicates that host factors that influence energy balance have a significant influence on the risk of developing colorectal cancer. Obesity and certain diets increase one's risk of developing colorectal cancer, while physical activity decreases this risk. Until recently, it was largely unknown if any of these modifiable factors influence the outcomes of patients already diagnosed with colorectal cancer. However, data are emerging of factors that may influence disease recurrences and mortality for colorectal cancer survivors. Prospective observational studies have shown that increased exercise after diagnosis and avoidance of a Western pattern diet are associated with reduced risk of cancer recurrence and improved overall survival in early stage colorectal cancer after standard therapy. Patients with class II and III obesity (BMI > 35 kg/m2) have a modestly increased risk of recurrence. In contrast, change of weight after diagnosis is not associated with outcomes after diagnosis. The data supporting these observations will be reviewed and potential mechanisms of actions will be discussed.