WASHINGTON — Elevated insulin levels and lifestyle factors were significantly associated with an increased risk of colon cancer in both white and African American subjects in a population-based study, Temitope O. Keku, Ph.D., reported at the annual meeting of the American Association for Cancer Research.
The study included 231 African Americans with colon cancer and 360 African American controls, along with 297 white patients with colon cancer and 530 white controls in North Carolina.
Cancer patients of both races reported eating significantly more food, compared with controls. Whites with cancer were significantly more likely than controls to report a high-fat diet, while African Americans with cancer were significantly more likely than controls to report NSAID use, Dr. Keku and her colleagues at the University of North Carolina at Chapel Hill wrote in a poster.
Comparison of the highest and lowest quartiles for insulinlike growth factor I showed a threefold increased risk of colon cancer among African Americans and a 1.6-fold increased risk among whites in the highest quartiles compared with the lowest quartiles.
Elevated insulin and C-peptide levels were positively associated with cancer in both races, as were elevated IGF-I levels, higher body mass index, and low levels of physical activity. In addition, high levels of IGF-I significantly increased the risk of colon cancer in overweight or obese subjects.
These interactions suggest that lifestyle and dietary factors may modify the link between insulin resistance and colon cancer, regardless of race.