Pre-existing psychological disorders, diabetes, and pancreatic cancer: A population-based study of 38,952 Finns

Background: It remains unclear how pre-existing depression, anxiety, and diabetes of different durations are associated with the risk of pancreatic cancer, its clinical characteristics, treatment modalities, and subsequent survival. Methods: From a register-based random sample of Finns residing in Finland at the end of the period 1987-2007, 6492 patients diagnosed with primary pancreatic cancer in 2000-2014, and 32 460 controls matched for birth cohort and sex, were identified. Pre-existing depression, anxiety, and diabetes were ascertained from the records of prescribed medication purchases. Information on pancreatic cancer outcomes was obtained from the Finnish cancer register. Data were analyzed using logistic and Cox regressions. Results: The risk of developing pancreatic cancer was found to be associated with long-term anxiety (treatment started 36 + months before the cancer diagnosis) (odds ratio (OR): 1.13, 95% confidence interval (95%CI): 1.04-1.22) and long-term diabetes (OR 1.72, 95%CI 1.55-1.90), as well as with new-onset (treatment started 0-24 months before the cancer diagnosis) depression (OR 1.59, 95%CI 1.34-1.88), anxiety (OR 1.76, 95%CI 1.50-2.07), and diabetes (OR 3.92, 95%CI 3.44-4.48). However, the effects of these new-onset conditions were driven by cases that began treatment within 3 months before the cancer diagnosis (concomitant period). Patients with long-term depression, anxiety and diabetes and those with new-onset anxiety had a higher risk of not receiving standard treatments. Lower survival was found for pancreatic cancer patients with new-onset depression (hazards ratio (HR) 1.38, 95%CI 1.16-1.64). Survival was not associated with pre-existing anxiety or diabetes. Conclusions: The associations between pancreatic cancer risk and pre-existing depression and anxiety were mostly driven by concomitant effects. Individuals with diabetes, regardless of duration, should be closely monitored for pancreatic cancer. Pancreatic cancer patients with new-onset depression should be targeted to improve their survival.