Role of physical activity and diet after colorectal cancer diagnosis

This review summarizes the evidence regarding physical activity and diet after colorectal cancer diagnosis in relation to quality of life, disease recurrence, and survival. There have been extensive reports on adiposity, inactivity, and certain diets, particularly those high in red and processed meats, and increased risk of colorectal cancer. Only in the past decade have data emerged on how such lifestyle factors are associated with outcomes in colorectal cancer survivors. Prospective observational studies have consistently reported that physical activity after colorectal cancer diagnosis reduces mortality. A meta-analysis estimated that each 15 metabolic equivalent task-hour per week increase in physical activity after colorectal cancer diagnosis was associated with a 38% lower risk of mortality. No randomized controlled trials have been completed to confirm that physical activity lowers risk of mortality among colorectal cancer survivors; however, trials have shown that physical activity, including structured exercise, is safe for colorectal cancer survivors (localized to metastatic stage, during and after treatment) and improves cardiorespiratory fitness and physical function. In addition, prospective observational studies have suggested that a Western dietary pattern, high carbohydrate intake, and consuming sugar-sweetened beverages after diagnosis may increase risk of colorectal cancer recurrence and mortality, but these data are limited to single analyses from one of two US cohorts. Additional data from prospective studies and randomized controlled trials are needed. Nonetheless, on the basis of the available evidence, it is reasonable to counsel colorectal cancer survivors to engage in regular physical activity and limit consumption of refined carbohydrates, red and processed meats, and sugar-sweetened beverages.