DIABETES-MELLITUS AND PANCREATIC-CANCER MORTALITY IN A PROSPECTIVE COHORT OF UNITED-STATES ADULTS

Objectives: Diabetes mellitus and pancreatic cancer are known to be as sociated, but it is not known whether diabetes is a true risk factor, preceding development of the cancer, or if it is an early manifestatio n of the cancer. To address this uncertainty, we examined the associat ion of pancreatic cancer mortality and reported diabetes of at least o ne year's duration in a large, prospective study of United States adul ts. The vast majority of diabetes in this cohort is likely to be non-i nsulin-dependent diabetes. Methods: After 12 years of follow-up, 2,953 deaths from pancreatic cancer were observed in a cohort of 1,089,586 men and women who were cancer-free at study entry in 1982. Cox proport ional hazards models, adjusted for age, race, smoking, family history of pancreatic cancer, body mass index (wt/ht(2)), and education, were used to assess associations. Results: A history of diabetes was signif icantly related to pancreatic cancer mortality in both men (rate ratio [RR] = 1.49, 95 percent confidence interval [CI] = 1.25-1.77) and wom en (RR = 1.51, CI = 1.24-1.85). However, the strength of the associati on varied over the follow-up period. The death rate from pancreatic ca ncer was twice as high in diabetics as in non-diabetics during the sec ond and third years of follow-up (adjusted RR = 2.05, CI = 1.56-2.69) but only about 40 percent higher in years nine to 12 (adjusted RR = 1. 38, CI = 1.08-1.77). Conclusions: The small but persistent increased r isk of death from pancreatic cancer, seen even when the diagnosis of d iabetes preceded death by many years, supports the hypothesis that dia betes may be a true, albeit modest, risk factor for pancreatic cancer.