Insulin and insulin resistance linked to exocrine pancreatic cancer

Exposure to higher insulin levels and insulin resistance appears to mediate the association between type 2 diabetes and pancreatic cancer, new study findings suggest.

A relationship between diabetes and pancreatic cancer has long been recognized, the authors of the study note. The question, however, is whether diabetes is involved in the etiology of pancreatic carcinogenesis, or is simply the result of subclinical malignancy.To find answers, Dr. Rachael Z. Stolzenberg-Solomon and colleagues conducted a prospective case-cohort study that included data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. The current analysis, initiated in subjects without clinical evidence of cancer during the first 5 years of follow-up, is published in the Journal of the American Medical Association for December 14.Excluding patients with islet cell carcinomas, there were 169 patients with exocrine pancreatic cancer, with whom the authors compared a random sample of 400 subjects who were alive without a cancer diagnosis at year 5. All subjects were smokers who were ages 50 to 69 years between 1985 and 1988, followed for a median of 13.8 years.”After adjustment for age, years of smoking, and BMI, higher concentrations of glucose, insulin, and insulin resistance tended to show positive dose-response associations with pancreatic cancer,” the authors report. The presence of diabetes and the highest insulin quartile raised the risk 2-fold, and risks were greater among cases that occurred with longer follow-up time, findings that they say “support the veracity of our results.”The long, prospective follow-up means that elevated insulin and insulin resistance were probably not the consequence of pancreatic cancer, Dr. Stolzenberg-Solomon and her colleagues add.”Lifestyle changes to decrease glucose and insulin concentrations through weight reduction, increasing physical activity, and diet, such as decreasing saturated fat intake, could possibly impact pancreatic cancer development,” they conclude.(Source: JAMA 2005;294:2872-2878: Reuters Health: Oncolink: December 2005.)