Higher dietary glycemic load and total carbohydrate intake has been linked to increased risk of cancer recurrences or death among patients with stage III colon cancer. This finding suggests that diet and lifestyle modification can have a role in improving patient survival.

Lifestyle behavior is known to play a role in the development of colon cancer. Such risk factors as obesity and physical activity directly influence insulin levels. Recent studies have shown a direct link between host factors that lead to hyperinsulinemia and cancer recurrence and mortality in colorectal cancer survivors. However, how glycemic load and other related dietary intakes influences the survival of colon cancer patients was unknown.

This observational study had 1,011 stage III colon cancer patients report their dietary intake both during and 6 months after participating in an adjuvant chemotherapy trial. The research team assessed the influence of glycemic load, glycemic index, fructose, and carbohydrate intakes on both mortality and recurrence of the disease.

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Patients with the higher dietary levels of glycemic load and total carbohydrate intake had an 80% increased risk of cancer recurrence and death compared with those with the lowest levels. The correlation was even greater among patients who were overweight or obese.

Lead author Jeffrey Meyerhardt, MD, MPH, of the Dana-Farber Cancer Institute in Boston explained that the study does not prove that diets high in glycemic load and carbohydrate intake cause the recurrence of colon cancer. The results do strongly suggest that such dietary factors play a role. He said, “Our findings may offer useful guidance for patients and physicians in ways of improving patient survival after treatment.”

These new clinical findings are consistent with an observation made more than 50 years ago that cancer cells are “avid sugar consumers.”

“In light of our and other’s research, we theorize that factors including a high glycemic load may stimulate the body’s production of insulin,” Meyerhardt said. “That, in turn, may increase the proliferation of cells and prevent the natural cell-death process in cancer cells that have metastasized from their original site.”

This study was published in the Journal of the National Cancer Institute (2012; doi:10.1093/jnci/djs399).