Energy imbalance, fat, fiber, and pancreatic cancer: Role of insulin resistance

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A major obstacle in preventing pancreatic cancer is its virtually unknown etiology. Mounting evidence suggests that insulin resistance is involved in pancreatic carcinogenesis. To date, however, few epidemiologic studies have comprehensively investigated the role of lifestyle factors influencing insulin resistance in the etiology of this malignancy. The present study sought to examine this problem in a case-control study conducted in Minnesota. Cases (n=186), aged 20 years or older, were ascertained from all hospitals in the metropolitan area of the Twin Cities and the Mayo Clinic; from the later, only cases residing in the Upper Midwest of the US were recruited. Controls (n=554) were randomly selected from the general population and frequency matched to cases by age (within 5 years) and sex. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression. After adjustment for confounders, physical activity was associated with a reduced risk but this protective effect was confined to light activity and moderate activity only [OR (95% CI) for highest vs. lowest quartile: 0.55 (0.30-0.97), p-trend = 0.038 and 0.51 (0.28-0.93), p-trend = 0.07, respectively]. An increased risk was found for dietary intakes of energy and fat, but no appreciable difference in the magnitude of the relations existed between saturated, monounsaturated, and polyunsaturated fat. Compared with individuals in the lowest quartile of fiber intake, the risk was approximately halved for those in the third (OR (95% CI): 0.49 (0.26-0.94) and the highest quartile [OR (95% CI): 0.52 (0.21-1.30)]. Our study lends support to the hypothesis that energy imbalance and dietary factors influencing insulin resistance modulate pancreatic cancer risk. Analysis of genetic markers is underway.